Engraved military dog tags are identification tags worn by soldiers and military personnel. They are intended to be used to identify military casualties. They are called "dog tags" because they strongly resemble the identification tags used to re-unite lost dogs with their owners.
Some companies manufacture engraved dog tags for both dog and human identification purposes.
Military personnel may wear two identical dog tags, one to be kept with the body and the other collected for notification purposes. Some countries issue dog tags that can be broken into two identical pieces for the same purpose. Most dog tags simply provide identification information but some also provide basic medical information, such as blood type.