If you're interested in online privacy but feel like you could use some more background, Google now has a YouTube video it says is meant to 'explain basic privacy concepts via video.'
It's a quick, 4 1/2 minute overview of just what Google saves in its search logs, which was the subject of a fair bit of welcome competition recently as the major engines tried to one-up each other with privacy policy upgrades.
The video is clear and accurate, but it's of course meant to make Google look good, so take it with a grain of salt. The engineer giving the presentation downplays what it means to tie searches together with an IP address and (more importantly) a unique ID, but the New York Times made it clear how that alone can be enough to track people down last year when AOL released detailed search records.