The stripe on a credit card, called a magstripe, is a magnetic stripe made of tiny iron based particles. These usually work well , but can be defective if it is exposed to powerful magnets, scratched or peeled off. The magstripe contains three stripes, all of them different. Track one has 210 bits to an inch, track 2 has 75 bits to an inch, and track 3 also has 210 bits to an inch. Different bank information is held by each of these stripes and can be read by special computers.