If you have location history turned on, Google will track where you go.
Google will also track your search in a bunch of different categories if you have Search History turned on.
It was actually pretty interesting to see what ads I've clicked on.
Google can serve you interest-based ads because it has a bunch of data about you, including your age, gender, languages you speak, and what it thinks your interests are.
next slide will load in 15 secondsSkip AdSkip AdSome of my interests were on-point, but others felt pretty random. Dictionaries and encyclopedias?
Google also keeps track of what devices you use and when you were last active on them.
Wanna know how many emails you've ever sent or contacts you have? Google keeps track of that too.
Ditto with your Google Talk contacts and purchases through Google Wallet.
Google stores what apps use your info.
next slide will load in 15 secondsSkip AdSkip AdNow, for a different side of things...