Magnetic stripe card facts for kids

A magnetic stripe card is a plastic card that has a special magnetic strip on its back. This strip can hold different kinds of information, like a tiny computer memory. It's made of tiny particles of iron or other metals. Information is stored by changing the magnetism of these particles, similar to how old video or audio tapes work.

These cards are used for many things today:

• Bank cards: Like debit or credit cards you use for shopping.
• Tickets: For buses, trains, or even parking lots.
• Keys: Many hotels use them as keys for rooms.
• Work tracking: Some companies use them to track employee working hours.

To read the information on a magnetic stripe card, you usually "swipe" it. This means sliding the card through a special slot on a machine called a reader. These readers can be separate devices or built into other machines, like a payment terminal at a cash register in a store.

Cards that can also do calculations themselves are called smart cards.

How Magnetic Stripe Cards Work

The way information is stored on these cards follows a standard called ISO 7811. Think of the magnetic stripe as having three separate "tracks" or lines where data is kept.

• The first track can hold up to 76 letters and numbers.
• The second track holds up to 37 numbers.
• The third track holds up to 104 numbers.

The first two tracks can only be read, meaning you can get information from them but not change it. The third track can be both read from and written to, which means new information can be added or changed on it.

Security and Newer Cards

In the past, bank cards sometimes stored a special code called a PIN on the magnetic stripe. Today, when you use an ATM or a payment machine, the machine sends a special code from your PIN to the bank's computer. The bank's computer then checks if it's correct. This makes it much safer because your actual PIN is not stored on the card itself.

Many payment cards around the world are now using a newer, more secure technology called EMV. These cards often have a small metal chip on them. However, most of these newer cards still have a magnetic stripe. This is so they can still be used in places that don't have the new EMV chip readers yet.

Images for kids

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  Backside of a bank card with a magnetic stripe

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  Visualization of magnetically stored information on a magnetic stripe card (recorded with CMOS-MagView, dark colors correspond to magnetic north, light colors correspond to magnetic south)

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  The first prototype of magnetic stripe card created by IBM in the late 1960s. A stripe of cellophane magnetic tape is fixed to a piece of cardboard with clear adhesive tape

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  Front side of the first magnetic stripe plastic credit card. Note that the narrow magnetic stripe is on the front of the card. It was later switched to the back side.

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  Back side of the first magnetic stripe plastic credit card

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  Back of early magnetic striped encoded paper card. The narrow magnetic stripe in the center of the card was applied using a magnetic slurry paint.

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  Example of a card from the late 1980s used in food vending machines in the UK

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  Detailed visualization of magnetically stored information on a magnetic stripe card (recorded with CMOS-MagView, dark colors correspond to magnetic north, light colors correspond to magnetic south).

See also

In Spanish: Tarjeta de banda magnética para niños