PDA, the full name of the English Personal Digital Assistant, that is, personal digital assistant, generally refers to the handheld computer. Compared to traditional computers, PDAs have the advantage of being lightweight, compact, and mobile without losing the power of their functions, and the disadvantage of having too small a screen and limited battery life.PDAs usually use a stylus as the input device, and a memory card as the external storage medium. In terms of wireless transmission, most PDAs have infrared and Bluetooth interfaces to ensure the convenience of wireless transmission. Many PDAs are also capable of having Wi-Fi connectivity as well as GPS global positioning systems.