Passwords keep your personal information, including your UD records, protected. Your passwords are the equivalent of the key to the lock for your virtual life. Because account names are often publicly available, using strong passwords and managing them wisely are the most important ways you can protect your information and others' information entrusted to you.
Never share your password or PIN with anyone; if you think someone knows your password or PIN, change it.
In addition to keeping your password private, you should also choose strong passwords. A recent study of 32,000,000 passwords revealed in a security breach at a social gaming Web site showed that over 290,000 of their clients had chosen "123456" as their password.
If you choose a strong password, you protect yourself against password-stealers. If you don't reveal your password to anyone, you make sure that no one else will accidentally reveal your password.