The document defines and explains the International Securities Identification Number (ISIN). It is a 12-character alpha-numeric code that uniquely identifies securities, including stocks, bonds, and mutual funds, for settlement purposes. The ISIN contains information about the issuer's country, security type, and check digit calculated using a modulo 10 algorithm. The ISIN system was developed in the 1980s and gained global acceptance in the 1990s to facilitate electronic trading of securities around the world.