Can anyone explain the special characters in preg matching?

[kobescoresagain]

Okay I am trying to learn preg matching and I am having some difficulties. Could someone explain all of the special characters and such to me? I just don't know which ones mean what.

[Xenon]

why not just look up at php.net?
http://de2.php.net/manual/en/function.preg-match.php

all patterns, chars... are listed there with some good examples as well :)