A magnetic stripe card is a means of storing data on a card using a band of magnetic material, which is read when the card is passed by a reading head. They are commonly used for things like bank cards and travel tickets.
They first saw use on the London Underground in 1964, where they were used for travel tickets. They were further developed by IBM into the familiar plastic credit card format, and the standard for credit cards was adopted in the US in 1969, and internationally a couple of years later.
On plastic cards, the magnetic stripe is hot stamped on the plastic, while on cardboard cards, the magnetic stripe is applied with magnetic slurry paint or in the form of a hot foil stripe.
The magnetic stripes are usually either high-coercivity (usually nearly black in colour) or low-coercivity (usually light brown in colour). High-coercivity stripes require higher amount of magnetic energy to encode, and are harder to erase making them suitable for bank cards. Low-coercivity stripes require a lower amount of magnetic energy to record, and hence the card writers are much cheaper but the cards are easier to erase giving them a shorter lifespan. This makes them more suitable for applications such as train tickets.
Cards with magnetic stripes may also contain an integrated circuit (making them ‘smart cards’) with RFID tags or a magnetic field for proximity reading, or metal contacts to electrically connect the card to the reader.