This guide walks you through all the important considerations you'll need to know when selecting an ID card printer. One of our experts will be in touch with you shortly to discuss the best ID card printer for your organization. Magnetic stripes are a popular form of encoding data on cards that has been used for decades. Magnetic stripe cards work by storing data as a pattern of positive and negative magnetic stripe fields. When the card is read, that pattern is decoded and the information translated into a usable format. Data is usually stored on three separate tracks that each can hold a set number of characters. Each of the three tracks can be used for a different type of data, for example member number, member name, and expiration date.