A card reader is a card-reading device that covers a wide range of meanings because of the wide variety of cards.
A card reader is an interface device used to read and write multimedia cards as removable storage devices in a computer. Commercial versions of card readers can read security smart cards. Card readers are usually USB-enabled and can access memory cards in a variety of formats, such as CompactFlash and Secure Digital, and can be used as a flash drive when paired with an appropriate card reader. In addition, some printers have integrated card readers. Users can easily use the printer to print out their photos.
Disadvantages of card readers
Internal card readers, under the Windows operating system, will create a lot of empty "removable disks" in the computer, which will increase the inconvenience of ordinary use. (But now Windows Vista and Windows 7 have solved this problem, that is, insert a memory card will show its corresponding "dismounted disk", and remove the memory card after its corresponding "dismounted disk" will disappear immediately). The external version is less problematic, but it takes up a USB socket.