Latency

In telecommunications, the term latency is used to measure the amount of time it takes for data to travel from a sender to a recipient. Latency plays a role in determining the smoothness of real-time data communications over a network. When latency is low (less than 100 milliseconds), a connection may give the impression of not having any delay at all. This is important for time-critical applications like voice and video phone calls, and some kinds of online gaming.

If, for example, you call someone over the Internet using a connection with 500 milliseconds of latency, then you only hear the other person half a second after they speak, and vice versa. The higher the latency, the more difficult direct communications are. The situation is similar for computer games: If you are playing an online game and want to move your character forward, you generally press the button or move a dongle to give the forward command. But your character will only move forward once the instruction reaches the gaming server. When there are long delays in the connection, your character may appear to have moved on your screen, but not on other players’ screens because the instruction has not yet reached the server. This phenomenon is often referred to as lag.

From a user perspective, the basic rule is: the less latency, the better. A latency rating of around 20 milliseconds is ideal for nearly all consumer applications. It is especially important that your connections which run between you and your Internet service provider, and between your service provider and major servers, have low latency. Your Internet connection’s latency rating can never be lower than those. Modern technologies like optical fiber and 5G normally have lower latency than older network technologies. Often, copper phone lines are used for the last mile – the connection between your home and the main lines – even if the main lines are made of optical fiber. This setup results in higher latency.

Latency is measured using tiny data packages known as pings. A device sends a ping to a server or to another device on the network, which then sends it back. The sender measures the time it takes for the ping to return. The resulting measurement, which is shown in milliseconds, indicates the latency. In some cases, only the time required for a ping to return from a server to the sender is shown. This measurement is often called the ping. Many online games track and show the ping rate, so that players always know how fast their device’s connection with the gaming server is.

Because different servers have different processing times, latency may vary depending on what you are using the Internet for. For example, in extreme cases, the ping for one online game may be twice as high as the ping for a different online game.

Latency ratings affect the quality of Internet connections, but do not define the speed of your Internet connection. Latency is a value which indicates how much time it takes for small pieces of data to travel between two devices on a network, regardless of how high or low that network’s bandwidth is. The Internet connection speed (bandwidth), on the other hand, indicates how much data you can send and receive within a certain period of time. Latency is normally measured in milliseconds, while bandwidth is measured in megabits per second (Mbps).

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