A Wedge Reader works by inputting data to a software program as if the data were being typed into a computer keyboard. This now works through the USB port, but originally, wedge readers connected to a special computer keyboard connector, so in effect, they were "wedged" between the keyboard and the PC. This is useful when you want to enroll a user card number into a software application, or input card or keytag data into a database. The wedge reader can be removed and installed while the application is running.

A Virtual COM Port (VCP) Reader behaves as if it is connected to one of the PC's serial ports (COM1, COM2, etc), instead of a USB connector. This is useful when trying to adapt a new card technology, such as HF RFID to an application which was originally written for a reader which connected to a COM port. It is also easier to write applications for COM Ports. This type of reader requires a software driver which re-routes data so that it appears to be coming from the COM port instead of the USB Port. VCP readers must be installed before running the application, and cannot be uninstalled before the application is closed.

An H.I.D. Device Reader appears to the software as if it is a Mouse or trackball or other type of Human Interface Device. This is a Microsoft Windows convention. (It has nothing to do with the company HID Global). The reader does not require a software driver like the Virtual COM Port, and it can be removed and installed while the application is running.