Magneetstripes

Magneetstripes, or magnetic stripes, is a term used for thin bands of magnetizable material that store information. Depending on the context, it can refer to data-storage stripes on plastic cards or to naturally formed stripes of magnetization in rocks on the ocean floor. Both forms rely on magnetic domains whose orientation can be changed and read by specialized sensors.

On payment and identification cards, magnetic stripes are thin layers of ferromagnetic material embedded in the card. The stripe is organized into tracks that encode data by magnetizing small particles in different directions. The common formats in many cards include three tracks; Track 1 and Track 2 carry account numbers, expiration dates, and discretionary data, while Track 3 is less widely used. Writing is performed by a magnetic read-write head that applies a controlled magnetic field, and reading is accomplished by a magnetic sensor that detects the orientation of magnetic domains. ISO/IEC standards, such as 7811 and 7813, define stripe formats, encoding, and physical dimensions. While magnetic stripes remain in use, many systems are migrating toward chip-based (EMV) or contactless technologies due to security concerns.

Magnetic stripes on the seafloor arise from the recording of Earth’s magnetic field in cooling basalt at mid-ocean ridges. As magma erupts and solidifies, iron-bearing minerals align with the prevailing geomagnetic field. When the field reverses, new rocks acquire opposite magnetization, creating alternating bands of normal and reversed polarity. These stripes are mirror-imaged on either side of oceanic ridges and, together with radiometric dating, supported the theory of seafloor spreading and plate tectonics. Modern marine magnetometers map stripe patterns across oceans, contributing to paleomagnetic reconstructions and studies of plate motion.