A computer is an electronic device that processes data according to instructions stored in its memory. It accepts data as input, processes the data, stores and outputs the results. The main components of a computer are the input devices, output devices, system unit, CPU, memory, storage devices and communications devices. Computers provide advantages like speed, reliability, storage and communication but also have disadvantages like privacy violations, health risks and environmental impacts. Networks connect computers together via transmission media like cables, satellites and phone lines to share resources and information. Software programs tell the computer what to do and are divided into system software and application software. Computers are used in many fields like education, finance, government, healthcare, publishing and more.