passing a variable between URL's

Here is the situation. somerandomsite.org/pageA.php has a link to somerandomsite.org/pageB.php when a user clicks on the link in pageA.php, I want to set a variable and pass it to pageB.php. I have seached the docs and the only two solutions I can come up with are the use HTTP GETS or cookies. Any other solutions? Is any one solution better than the others? Also, my assumption is that PHP handles regular expressions. Any documentation on that? So far the PHP docs have yeilded few clues in the subject. Thanks, ~Scott Thompson