In computing, the back-end is the part of a program or website that the user does not see or click. It is the hidden side: the machines and code that store information, look things up, and make the visible part work. When you tap a button on a phone, the back-end is what actually finds your account or saves your message. Programmers talk about back-end and front-end as a pair. Front-end is the screens and buttons; back-end is the machinery behind them. It is workplace and tech talk. Though actually, people also write backend as one word, with the same meaning. This entry is that computer sense, not “the back of a building.”