Rank is a value from 1 to 50. The scale is solely influenced by game time rather than skill or any other determining factor. A new rank is reached when a player has obtained a specific amount of experience which lengthens every level. Capture and Hold is unlocked at level 3 and Arena is unlocked at level 8.
Each Rank has a unique associated name and icon.
Below is a rough curve of XP needed to level up.