Ping!

Ping works like in a submarine where I am sure the word came from. It sends a "signal" out and waits for a 'signal' to come back. How long it takes can be translated into distance, for a submarine ping, or for computers how long it takes to communicate with the other computer.

Low ping is best. Normal pings for a local network should be around 0 to at most 10ms. On the internet it depends on how far away you are from the server, how many routers/switches it must go through, and overall network trafic. Normal pings should be around 20 to maybe 50 ms for a fast connection. I have seen pings for some sites at 300+
In gameing ping translates into lag. The higher the ping the longer it will take for your movements to be seen by the server and other players. Likewise you will see there movements after they have actually done them. EX: You may have a person in your sights on UT and fire. Due to high ping/lag when you fired the person had already moved out of the way, hence you will miss them.
Ping time isnt always better on fast internet connections. Some of it depends on the speed the server is connecting at, load on the server, and over all power of the server.

If you getting a 0 ping on an internet server than something isnt right which is probably why your getting lag.
Yes you can have a low ping and still get lag if the server is underpowered or just trying to server too many players.
Its hit and miss. Some low pings will give more lag than a higher ping due to server speed. If you do get lag off a low ping server try disconnecting and reconnecting. Thats helped me on UT servers.

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