Some insecure apps and services use the UDID as a way to identify users. For example you can get some profile data from OpenFeint with the UDID. There are probably a ton of other small things like this, but overall I wouldn't worry too much.
And some secure ones used to use it for multi-factor authentication - e.g. you still username/password, but you can only do it on the device that you registered on.
However, use of UDID has been deprecated by Apple, and they are now rejecting some new apps that read it. You're meant to use a unique application-level ID instead.
You presented information which was wrong, thus the downvotes. Man up and take responsibility for your post rather than expecting others to correct your lack of research. Next time, don't guess what it means; look it up and present the correct information with a reference:
Disinformation implies wilful, and to a lesser extent malicious. I made an honest mistake and get patronised and abused.
I claimed nothing, I merely offered an answer, which happened to be incorrect. Being human, I make mistakes. FTR, Unique Data Item Description is what the military use the acronym UDID for, I made an innocent assumption. So I was hardly making false statements, as you claim.
Seeings as the second point sailed over your head, I'll spell it out. I proffered and answer without being patronising and snarky, I could've said to the OP "Google it...", but I made an effort to be a decent member of the community. What's your excuse?
See, nobody really cares that you got it wrong initially. What's annoying everybody, or at least me, is the extremely un-gracious way you handled being corrected. Instead of just looking it up, finding the answer, and saying thanks, you basically go nuts at everyone.
FWIW I didn't downvote. Another user already answered the question correctly, so a longer reply seemed redundant, but I wanted them to know which of the two answers was correct. I agree that wrong information does not necessarily merit a downvote, but it's to be expected.
