In video, a frame is one of the many still images which compose the complete moving picture. When the moving picture is displayed, each frame is flashed on a screen for a short time (nowadays, usually 1/24th, 1/25th or 1/30th of a second) and then immediately replaced by the next one. Persistence of vision blends the frames together, producing the illusion of a moving image.
The video frame is also sometimes used as a unit of time, being variously 1/24, 1/25 or 1/30 of a second, so that a momentary event might be said to last 6 frames.
The frame rate, the rate at which sequential frames are presented, varies according to the video standard in use. In North America and Japan, 30 frames per second is the broadcast standard, with 24 frame/s now common in production for high-definition video. In much of the rest of the world, 25 frame/s is standard.