Explanition
 

Can someone explain to me what udid is?

I can explain what spelling is.

Sorry I was rushing :(

So can u explain?

UDID is unique device identifier. It is unique for every apple device and it can be used to identify your iDevice on applications. For instance, Graal uses UDID to save your account so it knows it's "you". No one can use your UDID unless they manage to figure yours out. If they had a spoofer, they can enter the target UDID and steal their information. Basically, if someone enters your devices UDID and you play Graal, they'll have your account.

so in other words its not necessary to know what it does, its just important not to tell people that id,... if you know it anyway...

Ohh ok ty shawn (rep+)

And if u have a jailbroken device, you should get UDID changer.
Multiple graal accounts for the win.