A field is half of an interlaced video frame — either the odd-numbered horizontal lines (1, 3, 5...) or the even-numbered ones (2, 4, 6...), captured a sixtieth of a second apart from the other half. Two fields combine to make one frame. This was the foundation of analog and early digital television: a 60i broadcast actually delivered 60 fields per second, which the old CRT TV interlaced together to produce ~30 frames per second of complete pictures.
The trick worked beautifully on CRT displays, because the phosphor coating naturally held the previous field's glow while the next one was being drawn. The human eye stitched the two together and saw fluid motion at a higher apparent frame rate than the bandwidth actually allowed. The whole reason interlacing was invented in the 1940s was to halve the radio bandwidth needed for television, and fields are the mechanism by which that worked.
On modern flat-panel screens, fields are a legacy headache. Because each field is from a slightly different moment in time, anything that moved between them produces visible horizontal "teeth" — the famous combing artefact — when shown together on a progressive display. Modern playback uses deinterlacing to reconstruct proper full frames from the field pairs, ideally with motion-compensation to avoid blurriness. For a product team in 2026, fields exist only in ingest pipelines for old broadcast material; everything produced and delivered today is progressive, frame-based, and never thinks about fields at all.
