Not sure why this thread was moved to the PHP forum but whatever. I can answer the question pretty easily.
Card readers are practically standardized these days to be able to run with any Point-Of-Sale system. There are two flavors of card reader: Two stripe and three stripe. A two stripe magnetic card reader will read just two stripes of a credit or debit card and a three stripe will read all three stripes. Obviously, more stripes is better as you can pull off more information from the card. Modern card readers usually connect either via Bluetooth or USB and are usually capable of "keyboard emulation" mode. So, when you swipe a card, the device emulates pressing keys on the keyboard. There is usually software available to program the device so it ties into your application and "presses" the right keys at the right time to fill in various fields.
Virtually anything with a magnetic stripe that follows standards can be read with a standard magnetic card reader. A basic magnetic card reader will read credit and debit cards but also supposedly newer drivers licenses and some key cards.