What is big data concept

what is big data concept A practical information and advantages of Big Data for businesses. It is the size of the data which determines the value and potential of the data under consideration and whos whether it can be considered as Big Data or not. Why and how is it being used? Businesses today are seeking new and better ways to remain competitive, profitable and prepared for the future, and,. • There are many applications where simply being able to comb Mar 06, 2014 · Big Data is a big thing. Below, you can read about these features and requirements in more detail. May 06, 2020 · Big Data tools can efficiently detect fraudulent acts in real-time such as misuse of credit/debit cards, archival of inspection tracks, faulty alteration in customer stats, etc. 'Big Data' refers to data volumes that are so complex that conventional software and hardware used for processing data is no longer of any use. What is Big Data - really? There's nothing new about the notion of big data, which has been around since at least 2001. co/big-data-hadoop-training-certificationThis Edureka Big Data tutorial (. Big Data comes from a great variety of sources and generally is one out of three types: structured, semi structured and unstructured data. Part of what contributes to data being "big" is the sheer growth of the amount of data in the world. Examples of sociologic Sociological concepts are key ideas in the study of sociology, and are generally tau. ”Let's dig deeper and understand this in simpler terms. Another definition for big data is the exponential increase and availability of data in our world. So, what is big data? While there is no “official” definition, the main characteristics are commonly referred to as the four Vs – Volume, Velocity, Variety, and Veracity. ” This is how Oscar Herencia, General Manager of the insurance company MetLife Iberia and an MBA Professor at the Antonio de Nebrija University concluded his presentation on the impact of big data on the insurance industry at the 13th edition of OmExpo, the popular digital marketing and. The chapter explores the concept of Ecosystems, its origins from the business community, and how it can be extended to the big data context. And it is not related to computers only. What is defined, as big data may not be the same tomorrow? For instance, in future, with the advancements in the storage technologies, the data that is deemed as big data to. Big data refers to data sets that are too large and complex for traditional data processing and data management applications. The Big Data Value Chain is introduced to describe the information flow within a big data system as a series of steps needed to generate value and useful insights from data. 6 May 2013. According to IDC, “Worldwide revenues for big data and business analytics (BDA ) will reach $150. Sep 30, 2015 · Big data is not a fad. i. As Big Data tends to be distributed and unstructured in nature, HADOOP clusters are best suited for analysis of Big Data. Until recently, data was mostly produced by people working in organizations. This Hadoop tutorial will give you in-depth knowledge about What is Big Data Hadoop. What is Big Data? Big Data Definition. Big Data refers to large sets of complex data, both structured and unstructured which traditional processing techniques and/or algorithm s a re unab le to operate on. Big Data definition – the three fundamental Vs: Volume defines the huge amount of data that is produced each day by companies, for example. 14 Dec 2017. Feb 14, 2012 · Let us start with a very interesting quote for Big Data. Big data is data that is too large to process using traditional methods. People began storing their data in relational database systems but with the hunger for new inventions, technologies, applications with quick response time and with the introduction of the internet, even that is insufficien. 12 Dec 2017. It changes fast and comes in varieties of forms that are difficult . In fact, more and more companies, both large and small, are using big data and related analysis approaches as a way to gain more information to better support their company and serve their customers, benefitting from the advantages of big data. Future research directions in this field are determined based on opportunities and several open issues in Big Data domination. 10 Dec 2019. Big Data that is within the corporation also exhibits this ambiguity to a lesser degree. Jun 20, 2017 · Big data management is a broad concept that encompasses the policies, procedures and technology used for the collection, storage, governance, organization, administration and delivery of large repositories of data. See full list on zdnet. Variety makes Big Data really big. Apr 01, 2015 · 1. Si. Big Data is everywhere. How does Big Data work? Big Data works on the principle that the more you know about anything or any situation, the more reliably you can gain new insights and make predictions about what. Big Data. Big Data concept is new and hasn't evolved too much for offering a comprehensive understanding to gen. Big Data means a large chunk of raw data that is collected, stored and analyzed through various means which. But loads of people are still treating the concept of big data as. What is Big Data (2018)? (In 5 mins)Big Data basically refers to, huge volume of data that cannot be, stored and processed using the traditional approach wit. The authoritative definition of big data came from Doug Laney, who was an analyst at META Group, which has&nb. 26 Jun 2017. Trigger warning: authoritarianism, state surveillance, the Holocaust. As more. Big Data is analyzed by organizations and businesses for reasons like discovering patterns and trends related to human behavior and our interaction with technology, which can then be used to make decisions that impact how&. ” An award-winning team of journalists, designers, and videographers who tell brand stories through Fast Company's dist. Aug 15, 2013 · Big data is just another name for the same old data marketers have always used, and it’s not all that big, and it’s something we should be embracing, not fearing. And its impact is immense, regardless of industry. In a nutshell, Big Data is your data . Big data was originally associated with three key concepts: volume, variety, and velocity. Characteristics of big data include high volume, high velocity and high variety. 26 Aug 2019. Big Data therefore refers to our ability to make use of the ever- increasing volumes of data. Jan 05, 2015 · Big Data as the three Vs: Volume, Velocity, and Variety. The term Big Data is frequently associated with the specific technology that enables its utilization. Key Topics: Volume, Velocity and Variety Data Exhaust Technologies Hadoop Big Data Implications. This page contains a technical definition of Big Data. From the dawn of civilization until 2003, humankind generated five exabytes of data. This paper documents the basic concepts relating to big data. Nov 09, 2020 · This article intends to define the concept of Big Data, its concepts, challenges and applications, as well as the importance of Big Data Analytics 5V Concept Content may be subject to copyright. A data set can be considered big if the information system is either at its maximum capacity or cannot accomplish the task (Miklos Vasarhelyi, Alexander Kogan, and . Big data’s power does not erase the need for vision or human insight. com Social media, cloud applications, and machine sensor data are just some examples. We highlight the fact that size is only one of several dimensions of big data. The basic idea behind the phrase 'Big Data' is that everything we do is increasingly leaving a digital trace (or data), which we (and others) can use and analyse. For additional context, please refer to the inf. On the contrary, we still must have business leaders who can spot a great opportunity, understand how a market is developing. • Big Data analysis includes different types of data 10. The social network is exploring modular architecture partly to make its physical infrastructure “faster, leaner, smarter. Jun 30, 2020 · Big Data refers to the large amounts of data which is pouring in from various data sources and has different formats. The variety in data types frequently requires distinct processing capabilities and specialist algorithms. That’s not it. 4) Manufacturing. If Big Data only recently entered the supply chain management spotlight, then, it may be because the technology only recently reached the last layer to deliver insights. Remarks. Introduction. Feb 25, 2014 · Big Data is also geospatial data, 3D data, audio and video, and unstructured text, including log files and social media. Beane popularized the idea of correlating various statistics with under-valued player traits in order to field an A's baseball t. Some have defined big data as an amount of data that exceeds a petabyte—one million gigabytes. 3 Vs of Big Data : Big Data is the combination of these three. “You can't manage what you don't measure. You could say that Big Data describes huge data volumes, both unstructured and structured, that is generated […] Feb 28, 2014 · The basic idea behind the phrase 'Big Data' is that everything we do is increasingly leaving a digital trace (or data), which we (and others) can use and analyse. Big data refers to the 21st-century phenomenon of exponential growth of business data, and the challenges that come with it, including holistic collection, storage, management, and analysis of all the data that a business owns or uses. Jul 03, 2019 · As analyst and author Doug Laney puts it, big data is defined by three Vs: volume, velocity and variety. 21 Mar 2018. Big data is high-volume, high-velocity and/or high-variety information assets that demand cost-effective, innovative forms of information processing that enable enhanced insight, decision making, and process automation. The concept of big data and its importance has been around for years, but only recently has technology enabled the speed and efficiency at which large sets of data can be analyzed. techtarget. This is the second course in the Data Warehousing for Business Intelligence specialization. Variety of Big Data. By definition, Big Data is data that contains greater variety, arriving in increasing volumes, and finally with ever-higher velocity. Feb 13, 2017 · By this definition, Big Data as a concept requires three distinct layers before application: more data, processing systems, and analytics. Ideally, the courses should be taken in sequence. big data (infographic): Big data is a term for the voluminous and ever-increasing amount of structured, unstructured and semi-structured data being created -- data that would take too much time and cost too much money to load into relational databases for analysis. Google Trends chart mapping the rising interest in the topic of big data. It can process and store a large amount of data efficiently and effectively. 23 Mar 2015. Decoding the human genome originally took 10 years to process; now it can be achieved in one week - The Economist. Now, that you have a sheer idea of what is big data, let's check out the major sectors using Big Data on an everyday bas. Sep 25, 2013 · In a nutshell, Big Data is your data. Two of the most famous Big Data prognosticators/pioneers are Billy Beane and Nate Silver. These data sets are so voluminous that traditional data processing software just can’t manage them. Capturing, storing and generating value from Big Data raises a number of technical and conceptual challenges that go. The concept of Big Data is a relatively new one and it represents both the increasing amount and the varied types of data that is now being collected. If you're in the big data business, there's a huge privacy issue that isn't addressed as often as it should be. Jan 31, 2021 · As Gartner defines it – “Big Data are high volume, high velocity, or high-variety information assets that require new forms of processing to enable enhanced decision making, insight discovery, and process optimization. I remember my first computer which had 1 GB of the Hard Drive. Big Data Basics. Big Data is not a technology related to business transformation; instead, it enables innovation within an enterprise on the condition that the enter-prise acts upon its insights. It covers the range of concepts, approaches and techniques that are applicable to Data Analysts, for which learners are required to Jun 14, 2017 · The concept of Big Data is nothing new. This infographic explains and gives examples of each. Big Data is a phrase used to mean a massive volume of both structured and unstructured data that is so large it is difficult to process using traditional database and software techniques. In most big data circles, these are called the four V's: volume, variety, velocity, and veracity. But these massive volumes of data can be used to address business problems you wouldn’t have been able to tackle before. The extent of the dataset size and the complexity of operations needed for its processing entail stringent memory storage and computati. There's lots of it flowing in at great speeds from numerous sources. Data which are very large in size is called Big Data. The analysis of big data presents challenges in sampling, and thus. Big data is a prominent term which characterizes the improvement and availability of data in all three formats like structure, unstructured and semi formats. See full list on searchbusinessanalytics. It was the basis of. It attempts to consolidate the hitherto fragmented discourse on what constitutes big data, what metrics define the size and other characteristics of big data, and what tools and technologies exist to harness the potential of big data. No, hold on. 23 Oct 2014. In this course, you will learn exciting concepts and skills for designing data warehouses and creat. In other words, big data gets generated in multi terabyte quantities. Conception may happen on purpose or by happy accident. 🔥 Flat 20% Off (Use Code: YOUTUBE20) Edureka Hadoop Training: https://www. Bigdata definition with 3V. 16 Jun 2020. This means that, at its essence, Big Data is a neutral term, as it'. There are Big Data solutions that make the analysis of big data easy and efficient. Using data elements consistently and reliably also allows for information to be collected once and reused for multiple purposes, including outcomes measurement, practice level improvements, surveillance, population health, research, and decision support. Structured data can be generated by machines or humans, has a specific schema or model, and is usually stored in databases. See full list on educba. Hadoop works better when the data size is big. What we're talking about here is quantities of data that reach almost incomprehensible proport. Big Data consists of an immense amount of electronic data generated from the internet and its sources including: clicks, search patterns, preferences, videos, and social media including Facebook, YouTube, Twitter, and more. It is important that this data come from credible sources, as the validity of the research is determined by where it comes from. Psychiatric Annals | The disease concept is rooted deeply in the beliefs, values, and epistemic state of a particular culture. Oct 25, 2019 · Big data in healthcare refers to the vast quantities of data—created by the mass adoption of the Internet and digitization of all sorts of information, including health records—too large or complex for traditional technology to make sense of. Section 2 explains fundamental concepts and describes the rapid growth of data volume; Section 3 discusses. But, do you really know what it is and how it can help your business? SAS perfectly captures Big Data as “a term&. 30 Oct 2020. It is traditionally considered (and suggested by Oracle in the article, mentioned above) that big data is described by three main concepts: volume, velocity, and variety. The aim in analyzing all this data is to uncover patterns and connections that might otherwise be invisible, and that might provide valuable insights about the users who created it. 12 Jul 2019. We call this Big Data Search” says David Gorbet. December 09, 2015. Students are asked to consider how much of their lives are “datafied” or could be, and the teacher will show the projected growth of data in the world. According to TCS Global Trend Study, the most significant benefit of Big Data in manufacturing is improving the supply strategies and product quality. While the problem of working with data that exceeds the computing power or storage of a single computer is not new, the pervasiveness, scale, and value of this type of computing has greatly expanded in recent years. 10 Sep 2018. The amount of data accumulated by private companies, public agencies, and other . Later studies pointed out that the definition of 3Vs is insufficient to explain the big data. 31 Mar 2015. 18 Oct 2019. 26 Nov 2016. Access, manage and store the data. In informa. It u. Gorbet’s concept of “Big Data Search” implies the following: • There is no single set formula for extracting value from Big Data; it will depend on the application. It originated with Web search companies who had the problem of querying very large distributed aggregations of loosely-structured data. com Sep 28, 2016 · Big data is a blanket term for the non-traditional strategies and technologies needed to gather, organize, process, and gather insights from large datasets. An example is the use of M and F in a sentence—it can mean, respectively, Monday and Friday, male and female, or mother and father. As you can see from the chart, the amount of data flying around is growing exponentially, doubling every two years or so. We then expand the discussion on variou. Jul 13, 2016 · The importance of big data lies in how an organization is using the collected data and not in how much data they have been able to collect. According to Wikipedia, Big data is “an all- encompassing term for any collection of data sets so large or complex that it becomes difficult to process them using traditional data-processing applicati. In HGTV's series Open Concept, Dallas sisters Whitney and Ashley are transforming family homes into chic masterpieces with smart, functional spaces. The concept of Big Data is nothing new. master-piece(マスターピース)の財布「noble」(525080)を購入できます。. 27 Jul 2017. com Mar 27, 2019 · Veracity: the quality, accuracy, or trustworthiness of the data. This much seems true: Entrepreneurs who start businesses that are in line with their field of expertise, such as startups that follow in the professions of corporate jobs their owners once held, are 40 percent more likely to make it, accord. They all talk about it but no one really knows what it’s like. What is Big Data? By Molly Galetto. It comes under a blanket term called Information. To get to the heart of what big data means, here's Gartner's definition: Big data is high-volume, high-velocity and high-variety information assets that demand cost- effective, innovative forms of information process. ” Big data is a concept not a technology which will help us to handle below mentioned criterias. 16 Apr 2020. Organizations collect data from a variety of sources, including business transactions, social media and information from sensor or machine-to-machine data. Correspondingly, the definition of disease is as broad or as narrow as may be held in the mind of the user of the. Big data is a collection of large datasets that cannot be processed using traditional computing techniques. At a high level, a big data strategy is a plan designed to help you oversee and improve the way you acquire, store, manage, share and use data within and outside of your organization. Thought Leadership. A Comprehensive Big data Guide - 2020. com BCS Level 4 Diploma in Data Analysis Concepts Version 4 July 2020 Introduction This Diploma is the second module of the two knowledge modules required for the Level 4 Data Analyst apprenticeship programme. 14 May 2017. For those struggling to understand big data, there are three key concepts that can help: volume, velocity, and variety. 14 Jun 2017. That is why when we are speaking about Big Data, we are always talking about the “Big Vs. Nov 03, 2017 · Big data is the data that is characterized by such informational features as the log-of-events nature and statistical correctness, and that imposes such technical requirements as distributed storage, parallel data processing and easy scalability of the solution. According To Wikipedia, Big data can be described by the following: Volume – The quantity of data is generated that is very Important in esta context. But wha. • Traditional database systems were designed to address smaller volumes of structured data, fewer updates or a predictable, consistent data structure. A clear big data definition can be difficult to pin down because big data can cover a multitude of use cases. 10^15 . In the business world, these are the high-level dim. Apr 12, 2019 · Having a goal, an explicit purpose in collecting and analyzing a dataset, is how scientists can harness the power of data to solve problems and answer questions. 8 billion in. Make data-driven decisions. On the premise of this definition, the properties of big data are reflected by 3V's, which are, volume, velocity and variety. Structured data is augmented by unstructured data, which is where things like Twitter feeds, audio files, MRI images, web pages, web. Apr 14, 2017 · Big data analytics refers to the strategy of analyzing large volumes of data, or big data. See full list on docs. Big data means a large set (petabytes or gigabytes) of structured, unstructured or semi-structured data and analyzing those data to get the insights of the business trend. Sometimes, files duplicate some data. It's the information owned by your company, obtained and processed through new techniques to produce value in the best way possible. We are just at the beginning of a revolution that will touch every business and every life on this planet. So Wikipedia's definition is focusing on 'volume o. It will change our world completely and is not a passing fad that will go away. It can be defined as data sets whose size or type is beyond the ability of traditional relational databases to capture, manage and process the data with low latency. Jan 01, 2021 · Big data refers to the large, diverse sets of information that grow at ever-increasing rates. However, these three concepts do not adequately describe the phenomenon of big data without the fourth and fifth components, which are variability and veracity. What qualifies as “big” is also a relative concept. A Definition of Big Data. When information like names and addres. microsoft. Let’s have a look at a graph that shows us just how large big data is. “Big data is like sex among teens. Since it is processing logic (not the actual data) that flows to the computing nodes, less network bandwidth is consumed. It processes a huge amount of structured, semi-structured, unstructured data to extract insight meaning, from which one pattern can be designed that will be useful to take a decision for grabbing the new business opportuni. When this happens, it is important to match the data between files. We have now presented an example in which data, facts, documents and information are clearly distinguished as different concepts and will from this basis continue considering conceptual discussions in the scholarly literature. 14 Jun 2018. The Four V's of Big Data. • Chapter 3 shows that Big Data is not simply “business as usual,” and that the decision to adopt Big Data must take into account many business and technol- Apr 12, 2018 · Click to learn more about author Harnil Oza. I had told. Traditional RDBMS is used to manage only structured and semi-structured data. 26 May 2020. Data inconsistency occurs when similar data is kept in different formats in more than one file. Traditional Database Systems cannot be used to process and store a significant amount of data (big data). Big Data therefore refers to that data being collec. Social media, cloud applications, and machine sensor data are just some examples. It can include data cleansing, migration, integration and preparation for use in reporting and analytics. This is the most well-known definition, first coined by Doug Laney of Gartner over twelve years ago. 1) Set a big data strategy. In most enterprise scenarios the volume of data i. All definitions on the TechTerms website are&nb. com See full list on intellipaat. The term Big Data is commonly used to describe a range of different concepts: from the collection and aggregation of vast amounts of data, to a plethora of advanced digital techniques designed to reveal patterns related to. 11 Oct 2018. The generation of data is so large and complex that it can no longer be saved or analyzed using conventional data processing methods. In this article we tell you what the 4 V's of Big Data are and why they are so basic and important in this technology. Proponents of Big Data often refer to this as the “datification” of the world. edureka. But, do you really know what it is and how it can help your business? SAS perfectly captures Big Data as “a term that describes the large volume of data – both structured and unstructured – that inundates a business on a day-to-day basis. The public would call this big data in action: a mass of video footage combed by specially trained police analysts to solve an international crime. Data is growing every single day. Edwards Deming and Peter Drucker, and it explains why the recent explosion of digital data is so important. The evolution of Big Data includes a number of preliminary steps for its foundation, and while looking back to 1663 isn't necessary for the growth of data volumes today, the point remains that “Big Data” is a relative. How can you encourage conception when you're trying to get pregnant? Advertisement Conception may happen on purpose or by happy accident. Everyone talks about this concept, but very few could tell you a good list of benefits of Big Data or how it can help your business. The leading edge of big data and analytics, which includes data lakes for holding vast stores of data in its. 1 The use of big data technologies can help nurses and other healthcare providers improve. Seemingly as unclear as its definition is the purpose or value of Big Data. Normally we work on data of size MB(WordDoc ,Excel) or maximum GB(Movies, Codes) but data in Peta bytes i. Mar 21, 2019 · Big Data is both a concept and a field that corresponds to all techniques or methodologies for analyzing extremely large amounts of data that cannot be processed by traditional data-processing software due to their volume and complexity. In truth, the concept is continually evolving and being reconsidered, as it remains the driving force behind many ongoing waves of digital transformation, including artificial intelligence, data science and the Internet of Things. See full list on guru99. W. The big data concept has been around for many years. But in general the term refers to sets of data that are so large in volume and so complex that traditional data. IBM data scientists break big data into four dimensions: volume, variety, velocity and veracity. This blog post is written in response to the T-SQL Tuesday post of The Big Data. 30 Jun 2020. It is the overarching system used to manage large amounts of data so that it can be analyzed for business purposes, steer data analytics, and provide an environment in which big data analytics tools can extract vital business information. Google developed MapReduce t. Big Data Definition. Understanding the customer insights will. It explains in computing terminology what Big Data means and is one of many Internet terms in the TechTerms dictionary. There are various ways for researchers to collect data. In this lesson, students are introduced to the concept of “ big data,” where it comes from, what makes it “big,” and how people use big data to solve problems. Building on Gartner's definition, the concept of big data and what it encompasses can be better understood with four Vs: Volume. Keep reading to learn how researchers go about collecti. 30 May 2017. Since then, many others have tried to. 25 Feb 2020. Put simply, big data is larger, more complex data sets, especially from new data sources. 1 Nov 2016. Data that is unstructured or time sensitive or simply very large cannot be processed by relational database engines. It is not a single technique or a tool, rather it has become a complete subject, which involves various tools, technqiues and frameworks. The data usually had a specific structure. The concept gained momentum in the early 2000s when industry analyst Doug Laney articulated the now-mainstream definition of big data as the three Vs: Volume. . Instead, it provides tools for people to analyze the data, along with a high-level definition of what data ex. erwise be hidden. This concept is called as data locality concept which helps increase the efficiency of Hadoop based. 2011年2月17日. Even previously there was huge data which were being stored in databases, but because of the varied nature of this Data, the traditional relational database systems are incapable of handling this Data. Big data analysis challenges include capturing data, data storage, data analysis, search, sharing, transfer, visualization, querying, updating, information privacy and data source. Analyze the data. 20 Mar 2019. It encompasses the volume of information, the velocity or speed at which it is created and collected. Big data can be examined to see big data trends, opportunities, and risks, using big data analytics tools. The hottest privacy topic to make the headlines is the embarrassment your company. what is big data, analytics, tools and trends for companies to survive in. To understand the phenomenon that is big data, it is often described using five Vs: Volume. Big Data is ambiguous by nature due to the lack of relevant metadata and context in many cases. Big data became more popular with the advent of mobile technology and the Internet of Things , because people were producing more and more data with their devices. ” There's much wisdom in that saying, which has been attributed to both W. Big Data is a collection of data sets so large and complex that it becomes difficult to process using on-hand database management tools or traditional data processing application. As data - both structured and unstructure. From custom built-ins in every room to one of a kind handcrafted furniture pieces, these cr. e. The definition of the big data on the basis of 3Vs is relative. Other characteristics, such as the frequency with which data are generated, are equally important in defining big data. Big data has made once-holistic concepts, such as “what consumers want,” more measurable. This is a very interesting subject. Download. If you want to avoid these topics, please jump to the last paragraph of this introduction, starting with ‘Enough about the depressing stuff. Refinement is hence required to add value. Big Data is a broad spectrum. The term “Big Data” refers to the collection of all this data and our ability to use it to our advantage across a wide range of areas, including business. If you look closely at this definition, you can see that it is framed in terms of time. Learn what is happening during conception and w. In most enterprise scenarios the volume of data is too big or it moves too fast or it exceeds current processing capacity. Through implementing big data analytics businesses can achieve competitive advantage, reduced the cost of operation and. Feb 25, 2019 · Big data refers to a process that is used when traditional data mining and handling techniques cannot uncover the insights and meaning of the underlying data. 'Big data' refers to datasets whose size is beyond the ability of typical database software tools to capture, store, manage, and analyze. Volume, velocity, variety, veracity and value are the five keys to making big data a huge business. com Jul 01, 2014 · The term Big Data is being increasingly used almost everywhere on the planet – online and offline. 27 Aug 2013. What Comes Under Big Data? Big data involves the data produced by different devices and applications. Large volumes of data are generally available in either structured or unstructured formats. 25 Sep 2013. This big data is gathered from a wide variety of sources, including social networks, videos, digital images, sensors, and sales transaction records. the five famous W's of journalism, Herencia's presentation was based on what he called the “five V's of bi. Sociological concepts are key ideas in the study of sociology, and are generally taught in introductory sociology classes and texts. ’ UX researcher, UX designer,. Big Data implies typically high volume, nonstatic, and frequently updated (velocity) data that involve a variety of data formats and particularly unstructured data, potentially wrong data (validity), and low value in its origin. what is big data concept