Different browsers have different default settings for page elements. In an effort to keep web pages looking as consistent as possible between browsers, many web designers use what is commonly referred to as a CSS reset to wipe away these default settings and start fresh.
Margin and padding are the most common things to reset as they commonly cause layout problems if not reset. This also gives you the opportunity to "work forwards" with your margin/padding. This means applying margin/padding only to elements which need it instead of removing it from elements that don't. This can often makes more sense for designers and can lead to trimmer code. Border is another popular thing to reset as it can take care of problems with those pesky borders around linked images. This can cause problems with borking* default styling for things like submit buttons that you didn't intend to bork.
Eric Meyer offers a popular reset and the star selector reset also enjoys some popularity. Both of these styles have their advocates and critics.
So how about it folks: What kind of CSS Reset Do You Use?
Do you use one of the popular ones? Have one of your own design? Do you use one at all? The voting widget is down in the sidebar as usual (RSS readers will have to make the jump to vote, still haven't figured that one out).
*Official term for screwing something up with CSS that you didn't intend to.