The standard form of identification for DoD employees is the Common Access Card (CAC) . The CAC is a "smart" card about the size of a credit card that is used to identify active duty uniformed service personnel, selected reserve, DoD civilian employees, and eligible contractor personnel. The CAC enables entry to installations and buildings, access to secured computer networks and systems, and documents affiliation with the DoD. The CAC must be safeguarded and secured at all times and protected from loss, theft, and misuse.