Dog tags are usually fabricated from a corrosion-resistant metal.
The tags are primarily used for the identification of dead and wounded soldiers; they have personal information about the soldiers and convey essential basic medical information, such as blood type and history of inoculations.
The tags often indicate religious preference as well.
The first tag, an octagonal green disc, was attached to a long cord around the neck.
The second tag, a circular red disc, was threaded on a 6-inch cord suspended from the first tag.
The first tag was intended to remain on the body for future identification, while the second tag could be taken to record the death.
British and Empire/Commonwealth forces (Australia, Canada, and New Zealand) were issued essentially identical identification discs of basic pattern during the Great War, Second World War and Korea, though official identity discs were frequently supplemented by private-purchase items such as identity bracelets, particularly favoured by sailors who rightly believed the official discs were unlikely to survive long immersion in water.This duplication allows one tag (or half-tag) to be collected from a soldier's body for notification and the second to remain with the corpse when battle conditions prevent it from being immediately recovered.The term "dog tags" arose because of their resemblance to animal registration tags.The British Army introduced identity discs in place of identity cards in 1907, in the form of aluminium discs, typically made at Regimental depots using machines similar to those common at fun fairs, the details being pressed into the thin metal one letter at a time.Army Order 287 of September 1916 required the British Army provide all soldiers with two official tags, both made of vulcanised asbestos fibre (which were more comfortable to wear in hot climates) carrying identical details, again impressed one character at a time.The Prussian Army issued identification tags for its troops at the beginning of the Franco-Prussian War in 1870.