Why does facebook change the url when I click on a link?

问题

Suppose that I click on a facebook link -- once clicked, the URL is transformed to this:

http://www.facebook.com/l.php?u=http%3A%2F%2Fapple.stackexchange.com%2Fquestions%2F398%2Fhow-do-i-build-apps-to-my-jailbroken-ipad&h=uAQFM5WKt

And then I'm redirected to the URL I thought I was going to. Why does facebook do this?

回答1:

Facebook keeps track of all the links fired from its website. It saves the url you provided as link.

First it forwards you to a facebook link where it saves the url and then it redirects to the actual url.

This way facebook knows which urls are getting most hits.

FYI, Even google does it.

来源：https://stackoverflow.com/questions/11045449/why-does-facebook-change-the-url-when-i-click-on-a-link