Data Mining refers to the mathematical techniques used to exam large data sets including but not limited to search histories or social media posts, looking for statistically significant inferences that will extract trends and patterns from the data. We leave data contrails behind as we conduct our lives online today. These digital wakes or contrails are closely examined by many companies for the predictive value they have on our decision making, choices, and future purchases.
A classic example is how Target determined a teenage girl was pregnant before her parents did. The father confronted his daughter asking why she had begun to receive diaper coupons in the mail and she admitted to being pregnant. She received these coupons from Target because her search history was data mined by this retailer who determined these search terms reliably predicted a pregnancy and therefore a future need for diapers.
Data Mining is performed on our personal public data every single day while we surf the web, post on social media, and consume content. We all have experienced our data being mined when we see advertisements for products we have recently searched for on Google or posted about on Facebook.
Source: NJIT, WindowsReport
Additional Reading: Why UPS trucks (almost) never turn left