Like computers, cars and PDAs, cell phones started out as purely functional pieces of technology, but quickly evolved plenty of fun frills to keep their users entertained. Today's phones have built-in video games, specialized background pictures, switchable faceplates and, of course, customizable ringtones.

A ringtone version of your new favorite song does serve some purpose, of course -- it lets you distinguish your own phone's ring from other phones ringing around you -- but more than anything else, it's a chance to add personality to technology.

In this edition of HowStuffWorks, we'll see what ringtones are all about, and we'll find out how you can add new tunes to your phone (if it's compatible). As we'll see, it's incredibly easy to find and add a song you like and load it up.