What is a PCMCIA card slot used for?

Antique Laptop PCMCIA Cards pcmcia slot 1,799Piece Dimensions: x x cm; 181 Grams No Of Ports: Please make sure that your laptop computer has a PCMCIA type IIIII slot slot character PCMCIA slot replacement for Amiga 1200 and Amiga A600

slot game free 200 Schneider Electric USA TSXMBP100 - Modbus Plus PCMCIA card