A computer is an electronic device that accepts data as input, processes the data, and provides output. It operates under instructions stored in its memory and can store data for future use. The main components of a computer are the input devices, output devices, system unit containing the processor and motherboard, and storage devices. Computers provide advantages like speed, data storage, and communication capabilities, but also have disadvantages such as privacy risks, health impacts, and environmental effects. There are several types of computers including handheld, personal, hybrid, laptop, and desktop computers.