Proximity, or prox card readers are data capture devices used to extract information stored on access control cards, contactless smart cards, and/or key tags. Proximity cards are part of contactless card technologies. Held near an electronic reader for a moment, they enable the identification of an encoded number. The prox reader usually produces a beep or other sound to indicate the card has been read.
A keycard is a security token that grants access through electrically-powered doors. These systems require a card reader that is installed on the door to gain access by tapping the card on the proximity reader. A proximity card is a contactless smart card which can be read without inserting it into a reader device, as required by earlier magnetic stripe cards such as credit cards and contact-type smart cards.
NOTE: If the reader doesn't beep/react when presenting a card format, it's not compatible with the reader.