What is jitter?

Question

Computer networks

I recently asked about the benefits of wired over Wi-Fi and someone mentioned jitter. Who can explain in simple terms what jitter is, how to calculate it and how pronounced it is in home networks.
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Answer 1

There are different concepts of jitter, the main one is a sharp change in the phase of the signal (for example, when playing two music tracks in sequence). However, in networks, jitter is usually referred to simply as "hopping ping", i.e. scatter in the transit time of network packets. Those. if all your packets go by 2 milliseconds, then there is no jitter. If all packets are 200 milliseconds long, then there is no jitter either. But if part of the packets goes by 2 and part by 200, then this is jitter. Jitter is present in almost any broadcast networks, incl. and in Ethernet, at high loads of the transmission medium. In WiFi, the severity of jitter will depend on several factors, the main one is the load on the private channel used. In an apartment building or office building with a bunch of small businesses, this can be quite a problem.
If you do not observe random ping delays even with a significant load on the network, then you do not have a jitter problem.

Answer 2

Literally, "trembling". That is, an unpredictable and unregulated change in some parameter. When applied to wifi, it usually means randomly jumping ping to the target server.
High jitter quite seriously complicates IP telephony - gurgling appears, third-party noise, words disappear. It complicates the work of IPTV - the image starts to break, crumble into squares, slow down, twitch ... Jitter is critical for real-time games, where moving the mouse a millimeter more or less may well mean the death of the character :D