Computer is an electronic machine that helps store and process data and instructions at high speed and accuracy. It can receive information, perform basic operations like calculations, and produce results according to given instructions. Data is raw facts represented by symbols, while information is data arranged in a useful order. A computer's main components are the central processing unit (CPU), control unit, arithmetic logic unit (ALU), memory, and input/output units. Memory includes primary memory like RAM and ROM, and secondary memory like hard disks, which can permanently store large amounts of data.