This function is used to check if an e-mail address is valid. It’s been created by Dave Child, and it’s probably one of the best e-mail validation functions out there (it actually follows all the specifications).

This function can be used in your scripts to use BBCode.

This popular MovableType function has been ported to PHP, by Adam Kalsey. Now you can create dirified filenames of any string you use this function with.

This function is used to URL encode strings so they can be sent through a URL. This function also makes sure all the characters have been transformed into their entities.

This function allows you to quickly calculate how many words a string contains. Very useful for word processor scripts!

This useful codesnippet can be used to create long strings, without having to escape ’single’ or “double” quotes, but $variables can still be parsed. Very useful for very long texts.