Or "network jitter" -- describes the VARIATION in the time it takes subsequent data packets to arrive over a network. For most types of data large variations between arrival times are acceptable. For networks that carry voice or video relatively small differences in arrival times cause perceptible disturbances in the recreated voice or video at the receiving end.

Because packet routing protocols such as IP generally rely on shared access to common transmission media (e.g. many asynchronous processes all sharing the same physical line) they tend to be characterized by relatively high jitter.

Jitter can be reduced with buffers. Buffering some incoming packets in a FIFO and then outputting them at a more regular rate reduces jitter. This is fine for data streams that are not interactive, such as music or videos. For interactive streams such as two-way phone conversations, this scheme will add latency, which reduces the quality of the conversation.