PHPmaster.com has a new introductory tutorial for those just starting out with PHP (or with programming really) talking about using looping structures for sets of data - for, while/do-while and foreach.

A significant advantage of computers is that they can perform repetitive tasks easily and efficiently. Instead of writing repetitive code you can write a set of statements that processes some data and then have the computer execute them repeatedly by using a construct known as a loop. Loops come in several different flavors in PHP: for, while, do-while, and foreach. I'll introduce you to each of them and show you how they can making repetitive tasks straightforward and easy to maintain.

The tutorial explains a use case for each of the loop types and includes a bit of sample code showing how to put it into practice. It also shares two special keywords that can be used to bypass or break out of your current loop - break and continue.