Do Google and Facebook keep track of the sites I browse outside of their own sites?

Question

I've noticed that on a lot of news sites and stuff, there is that icon that says "Share with Facebook" and sometimes even information about friends that have commented on the particular news article.

Does that mean that Facebook are not going keeping track of what I do on facebook, but also what I do on every facebook that has the "Share with Facebook" sign whether I like it or not? If so, what amount of information could they track? Just the fact that I went to that site or more specific information about me?

Same with google ads, a lot of sites have google ads - if I'm logged onto my gmail, does that mean google literally has a live web history of every site I've been to?

Is there any "blocker" apps I can download in order to prevent large companies from linking my web activities with my email or fb account?

Answer 1

Look at Ghostery...

Ghostery allows you to block scripts from companies that you don't trust, delete local shared objects, and even block images and iframes. Ghostery puts your web privacy back in your hands.

Works on:

• Firefox
• Google Chrome
• Safari
• Internet Explorer

@Sathya mentioned WidgetBlock and Disconnect.

Answer 2

Yep, they can track you, which is why there is all the recent hype over tracking cookies. All the upcoming browsers seem to be implementing a "do not track" list to block these cookies, and the EU has proposed fully outlawing them without user consent. Just because you visit www.*.com doesn't mean you only get cookies from them, Google will also drop a cookie on your PC for ad sense, which allows them to track everywhere you go from there. Cookies are not the only way they can track you just the most prevalent and easiest method, since every site tries to put cookies on your PC whether they are necessary or not. Just try browsing the web with No script on, cross requests blocked, and all cookies off, sure it's safe but it can get a little annoying. Personally I think I could deal with a much safer plain text web or you could just use Ghostery like Studiohack suggests.