Serial number

Despite being called serial "numbers", they do not need to be strictly numerical and may contain letters and other typographical symbols, or may consist entirely of a character string.

Serial numbers are a deterrent against theft and counterfeit products, as they can be recorded, and stolen or otherwise irregular goods can be identified.

Banknotes and other transferable documents of value bear serial numbers to assist in preventing counterfeiting and tracing stolen ones.

Serial numbers may be used to identify individual physical or intangible objects; for example, computer software or the right to play an online multiplayer game.

[1] During the Second World War RAF aircraft that were secret or carrying secret equipment had "/G" (for "Guard") appended to the serial, denoting that the aircraft was to have an armed guard at all times while on the ground, e.g., LZ548/G—the prototype de Havilland Vampire jet fighter, or ML926/G—a de Havilland Mosquito XVI experimentally fitted with H2S radar.

Prior to this scheme the RAF, and predecessor Royal Flying Corps (RFC), utilized a serial consisting of a letter followed by four figures, e.g., D8096—a Bristol F.2 Fighter currently owned by the Shuttleworth Collection, or K5054—the prototype Supermarine Spitfire.

In 2009, the U.S. FDA published draft guidance for the pharmaceutical industry to use serial numbers on prescription drug packages.