Overdraft protection is a service that automatically transfers funds from one bank account to another in order to avoid overdraft fees when insufficient funds are available. It can apply to savings accounts, checking accounts, lines of credit or credit cards. Overdraft protection carries its own fees, however. Previously, the service had frequently been automatically applied when an account was opened and the customer had to opt out. However, rules issued by the Federal Reserve in 2010 changed that, forcing banks to get your permission before you are enrolled.