Screenshots

A screenshot (or screen grab) is a digital image of what should be visible on a monitor, television, or other visual output device. A common screenshot is created by the operating system or software running on the device. A screenshot or screen capture may also be created by taking a photo of the screen.

The first screenshots were created with the first interactive computers around 1960. Through the 1980s, computer operating systems did not universally have built-in functionality for capturing screenshots. Sometimes text-only screens could be dumped to a text file, but the result would only capture the content of the screen, not the appearance, nor were graphics screens preservable this way. Some systems had a BSAVE command that could be used to capture the area of memory where screen data was stored, but this required access to a BASIC prompt. Systems with composite video output could be connected to a VCR, and entire screencasts preserved this way.

Screenshot kits were available for standard (film) cameras that included a long antireflective hood to attach between the screen and camera lens, as well as a closeup lens for the camera. Polaroid film was popular for capturing screenshots, because of the instant results and close-focusing capability of Polaroid cameras. In 1988, Polaroid introduced Spectra film with a 9.2 × 7.3 image size more suited to the 4:3 aspect ratio of CRT screens.

Screenshot support was added to Android in version 4.0 (Ice Cream Sandwich). In older versions, some devices supported screenshot functionality with one of the following combinations:

Screenshots can be taken by pressing Volume Down+Power, and are saved in the "Screenshot" folder in the gallery after a short sound and visual effect.

...
Wikipedia