Software Architect's Handbook

Latency

Latency is the amount of time (or delay) it takes to send information from a source to a destination. A phrase you may hear regarding latency is that it is the time spent on the wire, since it represents the amount of time a message spends traveling on a network. Something is latent if it is dormant and we must wait to perform any further processing while a message is traveling across a network.

Latency is usually measured in milliseconds. Factors such as the type of network hardware being utilized, the connection type, the distance that must be traveled, and the amount of congestion on the network all affect latency.

In many instances, a significant portion of the total latency takes place between your office or home and the internet ...