Magnetic strips are commonly found on credit cards, bank debit cards, prepaid telephone and vending cards, mass transit cards, drivers' licenses, employee ID badges, membership cards, school lunch programs library cards, gift certificates, loyalty cards and access control cards. This well-established technology is used in industries with low to medium data storage needs. The mag strip is a tape with metal filings that are arranged by magnetic energy that translates to readable characters. Options of magnetic strips include;

• 2 tracks - 2 lines of data, first line alpha, second line numeric
• 3 tracks - 3 lines of data, first line alpha, second & third line numeric

Mag strips come in two main varieties: high-coercivity (Hi- Co) at 4000 Oe and low-coercivity (Lo-Co) at 300 Oe but it is not infrequent to have intermediate values at 2750 Oe.

High-coercivity mag strips are harder to erase, and therefore are appropriate for cards that are frequently used or that need to have a long life.

Low-coercivity mag strips require a lower amount of magnetic energy to record, and hence the card writers are much cheaper than machines which are capable of recording high-coercivity mag strips. A card reader can read either type of mag strip, and a high-coercivity card writer may write both high and low-coercivity cards (most have two settings, but writing a Lo- Co card in Hi-Co may sometimes work), while a low-coercivity card writer may write only low-coercivity cards.