Jitter is the variation in the delay of received data packets over a network. In a perfect network, packets arrive at evenly spaced intervals. Jitter occurs when packets arrive unevenly due to network congestion, routing changes, or interference, causing gaps or bunching in the data flow. In live video streaming, jitter results in choppy or uneven playback. Streaming systems address jitter by using a small receive buffer to smooth out irregular packet arrival before decoding.