>>358183A regular expression is a way to define a text pattern. Imagine you want to search for "grey" but you don't know if the text contains "gray" or "grey" so with regular expressions you can search for
gr[ae]y
It's a pattern that describes both variants. Now this may seem kind of trivial, but consider you want to see if the user typed a valid email address. You'd use a pattern that includes letters, the @ symbol, and so on.
Anyway that's the quick rundown, here is a good online tutorial on regular expressions:
http://www.regular-expressions.info/If you give me an example or two of what kind of text you're looking for, I may be able to help.
