Virtual Keyboard

                      A virtual keyboard is a computer keyboard that a user operates by typing on or within a wireless- or optical-detectable surface or area rather than by depressing physical keys. Such a system can enable the user of a small handheld device, such as a cellular telephone or a PDA (personal digital assistant) to have full keyboard capability.

                     In one technology, the keyboard is projected optically on a flat surface and, as the user touches the image of a key, the optical device detects the stroke and sends it to the computer. In another technology, the keyboard is projected on an area and selected keys are transmitted as wireless signals using the short-range Bluetooth technology. Theoretically, with either approach, the keyboard could even be projected in space and the user could type by moving fingers through the air.

                  The term virtual keyboard is sometimes used to mean a soft keyboard , which appears on a display screen as an image map . In some cases, a software-based keyboard can be customized. Depending on the host system and specifc software, the user (who may be someone unable to use a regular keyboard) can use a touch screen or a mouse to select the keys.