Lag is a slow response from a computer. It can describe any device that responds slower than expected, though it is most often used in online gaming.
Video game lag is generally caused by one of two factors:
- A slow computer
- A slow Internet connection
If you are playing an online multiplayer game and your computer cannot process the incoming data in realtime, it may slow the game down for everyone. If your Internet connection is slow or inconsistent (which often happens with shared wireless connections), your system may not send and receive data quickly enough to keep up with other players. The lag may result in choppy frame rates and cause a delay between your input and what happens on the screen.
In an ideal world, all online gamers would have fast computers and Internet connections. In reality, players have a wide range of computer systems and Internet connection speeds. Therefore, game developers must account for lag in multiplayer games. One method is to use a central game server that makes sure one player's lag only affects the individual with the slow computer or Internet connection. It prevents players with high-quality gaming setups from being negatively affected by users with slow systems.
In some cases, a player with a high lag will be booted from a multiplayer game. For example, in StarCraft 2, if a player's system is not responding, a message will appear on the player's screen that says, "Waiting for Server." Other players in the game will see a message that says "Waiting for player: [player name]." If the lag is too high, the server will eventually boot the lagging player from the game.
Lag vs Latency
The terms "lag" and "latency" are sometimes interchangeable since they often refer to the same thing. However, latency is a more technical term, usually quantified by a specific amount. For example, the latency of a player's network connection may be equal to the ping response time between his computer and the server. High latency (over 120 ms, for example) can produce noticeable lag.
NOTE: "Lag" can also be used as a verb. For example, a player that is "lagging" may be slowing down the game.