A card reader is a hardware device that can read and write to a memory card or memory stick. It is often used to deliver data to computers or other devices for display and/or storage purposes.
Techopedia explains Card Reader
In the most basic sense, a card reader is used to access the contents of a memory card in a given format and passes them on to another device. Often, the memory card or stick shows up as a "mounted drive" on a computer or device. One of the biggest aspects of designing card readers is the range of drivers and software solutions needed to achieve the conversion from one format to another. The methods and strategies used in such conversion vary from one product to another, but, overall, manufacturers have made improvements in making USB card readers and other devices consistently universal, so that most recipient devices can recognize and read the data from a portable card or stick.