Your "Certificate of Release or Discharge from Active Duty", commonly known as "DD-214", is, possibly, the most important document that you will receive from the military. You cannot obtain VA benefits without presenting a DD-214.
Keep your original DD-214 (and all service documents) in a safe, fireproof place and make at least 10 certified copies. In most states, you can register or record your DD-214 with county or town registrar's office. Before doing so, however, you should inquire whether state or local laws permit public access to the recorded document. If public access is authorized, private identifying information may become available to the general public, which could compromise your privacy and financial security.
As an alternative, you can have your local VA Veterans (Vet) Center (discussed more fully below) certify your DD-214 and have a copy placed in its files. You can visit the VA's Vet Center directory online at www.va.gov/directory/guide/vetcenter.asp