A computer system is a combination of hardware and software that can be programmed to perform a variety of tasks. Hardware refers to the physical parts of a computer system, such as the processor, the memory, the monitor, the keyboard, the mouse, etc. Software refers to the programs that run on a computer system, such as the operating system, the applications, the files, etc. A computer system receives data from input devices, processes it according to the instructions in the software, and produces results through output devices. Computer systems can vary in size, shape, and functionality, depending on the purpose and design.