PayPal asks all customers to verify their PayPal account to help increase trust within the PayPal community. PayPal only asks you for essential information when you sign up, but as you transact with PayPal, they are under a legal obligation to know more about you.
When you get verified:
To get your account fully set up and become 'verified', log in to your PayPal account and then on the account 'Summary' page, click the down-pointing arrow below your name. Then complete the remaining steps highlighted in grey. Any steps you have already completed will appear highlighted in green.