A computer is a machine that uses electronics to input, process, store, and output data. Data is information such as numbers, words, and lists. Input of data means to read information from a keyboard, a storage device like a hard drive, or a sensor. The computer processes or changes the data by following the instructions in software programs. A computer program is a list of instructions the computer has to perform. Programs usually perform mathematical calculations, modify data, or move it around. The data is then saved on a storage device, shown on a display, or sent to another computer. Computers can be connected together to form a network such as the internet, allowing the computers to communicate with each other.