Customization is changing or replacing original content of the phone, like ringtones, wallpapers, icons, themes, that come with branded or unbranded phones. It also includes removing text message storage limit, mute camera shutter sound etc.

Branded Phones = Some network providers place their own ringtones, themes, icons, links etc within phone's software. (eg. vodafone/telenor, orange, t-mobile, rogers, cingular etc.) Debranding means removing all this content and restoring phone to it's original factory/generic condition. This will not damage phone in any way!