Fairly sure with the advent of the web, Google were the first to track users on a worldwide scale, via search, adsense, analytics, chrome etc. Facebook soon fol

Fairly sure with the advent of the web, Google were the first to track users on a worldwide scale, via search, adsense, analytics, chrome etc. Facebook soon followed with its popularity. Both provide free products. There may be added value for a seller to data collect though, of course.