Players' language preferences contains a common language.
Solo players can only be matched against other solo players, or a single party of two players.
Five-player parties can only be matched against other five-player parties.
Each team contains about the same number of parties.
The discrepancy between experience (measured by the number of games played) between the least experienced player and the most experienced player is minimized.
The highest skill Radiant player should be close to the same skill as the highest skill Dire player.
The discrepancy in skill between the most and least skilled player in the match is minimized.
Valve has stated that matchmaking tries to fulfil several criteria: