Magnetic stripe card

The stripe on the back of a magcard is a magnetic stripe, often called a magstripe. The magstripe is made up of tiny iron-based magnetic particles in a plastic-like film.

Your credit card typically uses only tracks one and two. Track three is a read/write track (which includes an encrypted[?] PIN[?], country code, currency units and amount authorized), but its usage is not standardized among banks.

The information on track one in a credit card is contained in two formats: A, which is reserved for proprietary use of the card issuer, and B, which includes the following:

• Start sentinel - one character
• Format code="B" - one character (alpha only)
• Primary account number - up to 19 characters
• Separator - one character
• Country code - three characters
• Name - two to 26 characters
• Separator - one character
• Expiration date or separator - four characters or one character
• Discretionary data - enough characters to fill out maximum record length (79 characters total)
• End sentinel - one character
• Longitudinal redundancy check (LRC) - one character

LRC is a form of computed check character.

The format for track two, developed by the banking industry, is as follows:

• Start sentinel - one character
• Primary account number - up to 19 chars
• Separator - one char
• Country code - three chars
• Expiration date or separator - four characters or one character
• Discretionary data - enough characters to fill out maximum record length (40 characters total)
• LRC - one character

See also: ISO 7810