A computer is an electronic machine that works under instruction to accept data input, store data, process the input, and display output. It is commonly used for education, research, and training. The document outlines the full form of computer, functions of a computer, types of computers including microcomputers, minicomputers, mainframes and supercomputers, components such as input, output, storage, processing and communication devices, and daily uses like writing, calculations, drawing, education, internet, and games.