In Call Of Duty Modern Warfare 2 what is prestige mode?

when you have reached the highest online rank. you can then enter prestige mode, where you will drop back down to level zero and lose everything. but you can get new and cooler emblems.

Answer

Just elaborating on what was stated above. In Modern Warfare 2, once you've reached level 70 you have the option to enter Prestige Mode. (This can be found in the barracks). Entering prestige mode unlocks new Titles and Emblems, as well as new challenges which in turn give you new titles and emblems. It also changes the symbol appearing next to your Gamertag, depending on what prestige you are at. There is a maximum of 10 prestiges, and a Prestiges: 1, 2, 5, 7, and 10 you get a bonus Create a Class slot allowing for a maximum of 10 various classes. The previous poster is correct though, prestiging sends you back to level 1 and you lose everything you've earned except your callsign and emblem.