[ShadowHeart]

Temporary internet files.

When you surf the internet, your browser saves (caches) all pages, images, etc, on your computer, so that the next time you visit the same page as you did earlier, the browser doesn't have to download all the images, etc over again, but instead can just use the ones on your computer. Which will speed things up, especially if you're on dial up. If you're on a high speed internet, it won't make as much of a difference. They are not necessary at all, you can safely delete them if you want. They do use up a lot of space on your harddrive if you don't clean them out very often.