Short answers, pulled from the story.
The frame is a single static image that the human eye perceives as movement through the persistence of vision. This optical illusion blends rapid succession of static images into a fluid narrative when flashed onto a screen at specific intervals.
North America and Japan use a broadcast standard of 30 frames per second while the rest of the world adopted 25 frames per second. NTSC television systems utilize a rate of 29.97 frames per second due to historical constraints of color broadcasting technology.
The 35 mm frame size measures 36 by 24 millimeters in a still camera but shifts dimensions when the film moves vertically in a motion picture camera. The maximum frame size for 35 mm film is 18 by 24 millimeters known as the silent or full aperture before sound tracks reduce the image area.
Historically video frames were represented as analog waveforms where varying voltages indicated light intensity in an analog raster scan. Modern video systems represent the frame as a rectangular raster of pixels in an RGB color space or a color space such as YCbCr.
Still frames are widely used on video platforms to show viewers a preview or a teaser and are frequently published from surveillance videos to identify suspect persons. Video of the J.F. Kennedy assassination have been often discussed frame-by-frame for various interpretations and still frames of Magnetic resonance imaging videos are useful for medical diagnostics.
Some animation shows characters leaving the edge of the film or malfunctioning to break the fourth wall and create humor. Techniques include split frames where the lower half of the previous frame and the upper part of the next frame show at once and gate hair jokes where an animator places fake gate hairs within the frame.