Everyone you send and receive to/from, everyone in your calendar and contacts, and if you have Google apps on your PC, smart phone or tablet everything that goes in and out of that device, all apps and hardware, locations, times, phone numbers, etc.

It's not like someone is reading it - it's all being logged and correlated. They have been doing this for years with each app and service, but what's new is they're combining and correlating the info accross the various apps and services.

"Google processes personal information on our servers in many countries around the world. We may process your personal information on a server located outside the country where you live."

If you have Google Earth or other G apps I suspect the app may be able to send info to G even by reading and indexing other info on the device. It is legit spyware, IMHO, because YOU authorized it when you clicked YES to the terms of use.

READ THE TERMS AND POLICIES YOURSELF BEFORE YOU CLICK "yes". If you don't agree, then uninstall all G apps and use other search providers. Otherwise it might be just fine for you and you might think its worth it.