screensaver

A screensaver is a computer program or feature that activates automatically after a period of user inactivity, replacing the current display with moving images, patterns, or information.

Historically developed for cathode-ray tube displays to prevent phosphor burn-in, early screensavers were simple geometric patterns or text. They became a standard feature in many operating systems during the 1980s and 1990s, with Windows, macOS, and various Unix-like systems offering built-in or optional packs.

Typical screensavers display animations, photographic slides, clocks, weather or news tickers, or corporate branding. Some include security options such as requiring a password to resume after activation.

Despite reduced risk of burn-in on modern flat-panel displays, screensavers persist for aesthetic reasons, privacy (disabling screen content when away), or as branding. Modern operating systems often replace traditional screensavers with dynamic wallpapers, lock screens, or automatic power-saving modes.

Technical notes: Screensavers are composed of modules (.scr on Windows; .saver on macOS) and are activated by the system idle timer. They may use GPU acceleration and specific rendering APIs; they typically exit when user activity resumes or when a power button is pressed.