Latency

Latency is the delay between data being sent and the same data being received. It is the time you spend waiting for a response after a request leaves your device, so it describes how long the data is held up rather than how much data is moving.

Latency is measured in units of time, usually milliseconds (ms). One millisecond is one thousandth of a second, so a latency of 60 ms means a message is delayed by 60 thousandths of a second before it arrives. It is not measured in bits per second: bits per second describe how much data is carried, not how long you wait.

For example, if you press a button in an online game and your character reacts 80 ms later, the connection has about 80 ms of latency. A lower latency feels more responsive because the delay is shorter. High latency can make a video call feel out of step, even when the connection can carry plenty of data.

Latency is not a measure of reliability or signal range; it only describes the delay. Bandwidth, the maximum amount of data a connection can carry in a given time, is a separate measure.