Servers are what you play on.
Servers are sorted into regions, which are:
- North America
- South America
- East Asia
The 3 Asia-Pacific servers (East Asia, China, Oceania) tend to be the hardest in difficulty for all game modes, as the average skill level of players in this region is usually higher. FFA/Experimental Mode in these servers are also full of slow-teams.
If a server has not many players or has been around for very long, it will not let any new players join, stay up for a while, then disconnect all players from the server.