Big data -- a term used with increasing frequency -- refers to the rafts of data that businesses collect on a day-to-day basis, both advertently and inadvertently. The number of avenues that data can be gathered from is always growing and becoming easier to access. By 2025, more than 150 trillion gigabytes of data will need analysis. But it's not the volume that matters, it's how businesses process and use the data that's important. Enter data scientists.