runnnig on steam

depends on the game.
Steam has an offline mode, just click on Steam on the top left corner of the Steam window and select "Go Offline" and you are now in offline mode.
If a game requires to be connected to the internet, then steam will notify you that you need to go to online mode to play.
while in offline, you won't get any game updates.

soulfood said:

hello if i am playing a game which is connected to steam, meaning it needs steam to run, am i "online" ? and am i down loading when i am playing the game (which is costing me money )? thank you

steam will not download any content while you are in any full screen application, it will be transmitting data to the servers, it shouldn't cost you anything unless you're on dial up anyway.