Significance of jitter

Consider a media player which plays video streams from a server. Assume that packets take 1 second in flight to reach the media player. This means the moment a user requests a video from the server, the very first packet will arrive after one second and successive packets will be sent immediately (ideally). In real world scenarios, intermediate node latencies, different return paths for different packets and network congestion can contribute to varying delays. To counter such effects, packets are buffered at the media player. The amount of packet buffering needed can be derived from the jitter values.