Google click-through URL?

[Bobhenry]

Have you noticed that when you click-through a link on Google SERPs, momentarily a google domain URL is shown which then redirects to the target URL?

Since clickthoughs to sites shown on SERPs contribute strongly to the site's ranking position, perhaps this google redirecting URL can be useful.

The URL is of the form:


http://www.google.com/url?sa=t&rct=j&q=&...r1bcCEoE7g



So does anyone actually know what the elements in the redirecting URL actually mean?
?sa
?rct
?esrc
etc

If we understood this it might be very instructive.