Summary
Latency, jitter and packet loss explain how responsive and stable a connection feels. They matter for video calls, gaming, remote desktops and voice services, even when headline download speed looks good.
Definition
Latency is the time it takes for data to make a round trip between your device and a remote service, usually measured in milliseconds. Jitter is variation in that delay. Packet loss is the share of data packets that do not arrive successfully. A connection can have high download speed but still feel poor if latency is high, jitter is unstable or packet loss appears during busy periods. For a moving decision, test these during real usage windows, ideally on Ethernet first, then over Wi-Fi in the rooms where you will work or stream.