Each level tier consists a range of levels. The number of levels in each tier is fixed at 25 levels per tier for the first 150 levels and increased to 150 levels per tier after prestige.
As you level up to a higher tier, the experience points required per level increases, making it harder to level up.
Prestige is where one reaches the maximum level of 150 and enters into the prestige tiers. The prestige realm is divided into 4 tiers, Bronze, Silver, Gold and Platinum.
The prestige realm is fixed at 7,000 experience points per level.