Well, naturally I have to start with big data because everybody talks about it, but nobody can exactly say what it is.
You can find many definitions of big data online.
Gartner explains Big Data as
"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."
This a very business-driven definition.
Technology vendors like Microsoft define it as:
“Big data is the term increasingly used to describe the process of applying serious computing power—the latest in machine learning and artificial intelligence—to seriously massive and often highly complex sets of information.”
Lots of tech-talk in a definition about data.
A more straightforward definition is given by big data expert Bernard Marr:
"Big data refers to our ability to collect and analyze the vast amounts of data we are now generating in the world."
In other words, all definitions above state it's not about the data itself , but the way we utilize the data which is now generated in a huge amount.
Mind you, big data today is small data, or just data, in a few years from now.
Big data, it's just data, only we now learn how to use it.