Big data is a term used to describe ever increasing huge data in the world. Let us analyze some reports. Worldwide, there are over 1.71 billion monthly active Facebook users which is a 15 percent increase year over year. YouTube will likely realize around 500 hours of video content being uploaded to the site every minute. In every 40 months since the 1980 as of 2012, every day 2.5 Exabytes (2.5×1018) of data is created. Every minute we send over 204 million emails and about 3.5 billion searches a day and 1.2 trillion searches per year worldwide in Google alone. In fact almost 90% of data was created in the past couple of years.
This huge amount of data can be collected and analyzed. Speed size and structure are the important factors in Big data.
Almost everything about Big data: http://www.ap-institute.com/big-data-possibilities.aspx