Magnetic stripe cards use, as the name suggests, a stripe of material on the back of the card that can be magnetically encoded. That stripe contains card identity information that makes every card unique. The card is approximately the same size and thickness as a standard credit card.
However, the electronic encoding on a security card is usually substantially different that the coding used by credit card manufacturers.
The stripe material used is referred to as high coercivity.
High coercivity magnetic stripes are made of magnetic particles that are not easily altered when introduced to a magnetic field.
When a high coercivity magnetic stripe is near a magnetic field such as a magnetized screwdriver, the information on the stripe will be not affected, unlike low coercivity cards used on credit cards that are subject to erasure.
These stripes are more durable and the encoded data is often encrypted.
The card is read by sliding the card through a reader. The “read head” inside the reader decodes the magnetic information and translates the data into a machine readable code that can be sent throughout the system to confirm access permission.
If permission is granted, the system transitions a relay that controls the lock holding the door closed to the protected space.
The lock unlocks and the user is granted access.