In multiplayer online video games, MMOs, MMMORPGs, MMOFPSs and FPSs ping (not to be confused with frames per second) refers to the network latency between a player's computer (client), and either the game server or another client (i.e. peer). This could be reported quantitatively as an average time in milliseconds, or qualitatively as low ping or high ping. The latter usage is common among players of first-person shooter and real-time strategy games. Having a low ping is always desirable because lower latency provides smoother gameplay by allowing faster updates of game data.
Ping is often wrongly conflated with latency. Ping has become synonymous with its measurement - latency (usually measured in milliseconds), but it is a tool to take that measurement.
High latency can cause lag. One may "lag out" due to unacceptably high latency. Servers will often disconnect a client if the latency is too high and it poses a detriment to others' gameplay. Similarly, client software will often mandate disconnection if the latency is too high. A high ping does not cause lag; rather, a high ping value is the result of lag. It may also make servers crash because of the instability.
Rather than using the traditional ICMP echo request and reply packets to determine ping times, game programmers often instead build their own latency detection into existing game packets (usually based on the UDP protocol).
Some factors that might affect ping include: network protocol engineering, Internet connection speed, the quality of a user's Internet service provider and the configuration of firewalls. Ping is also affected by geographical location. For instance, if someone is in India, playing on a server located in the United States, the distance between the two is greater than it would be for players located within the US, and therefore it takes longer for data to be transmitted. However, the amount of packet-switching and network hardware in between the two computers is often more significant. For instance, wireless network interface cards must modulate digital signals into radio signals, which is often more costly than the time it takes an electrical signal to traverse a typical span of cable. As such, lower ping can result in faster internet download and upload rates.