Picture & Audio Quality
Keyframe (I-frame)
A complete, independently decodable video frame used as a reference point, as opposed to frames that only store changes since the last one.
Keyframes let a player start decoding at any point — necessary for seeking, joining a live stream mid-broadcast, or recovering after a dropped connection. Frames between keyframes are much smaller since they only encode what changed, but depend on the preceding keyframe to decode correctly.