Finding your iPhone, iPod touch or iPad’s unique ID (UDID)

Every iPhone, iPod touch and iPad has a unique identifier number associated with it, known as a UDID (Unique Device ID). Your UDID is a 40-digit sequence of letters and numbers that looks like this: 0e83ff56a12a9cf0c7290cbb08ab6752181fb54b. It’s common for developers to ask for your UDID as they require it to give you beta copies of iOS apps.

Finding your UDID using iTunes