iPAQ presently refers to a Pocket PC an personal digital assistant first unveiled by Compaq in April 2000; the name was borrowed from Compaq's earlier iPAQ Desktop Personal Computers. Since Hewlett-Packard's acquisition of Compaq, the product has been marketed by HP. The device is the main competition to the Palm, but provides more multimedia capabilities using a Microsoft Windows interface. In addition to this, there are several Linux distributions that will also operate on some of these devices. Earlier, units were modular. "Sleeve" accessories, technically called jackets, which slide around the unit and add functionality such as a card reader, wireless networking, GPS, and even extra batteries were used. Current iPAQs have most of these features integrated into the base device itself.