The level cap represents the ultimate goal and culmination of the leveling process, with max-level characters having gained access to all class abilities and talents, and being able to access end-game content and equip the most powerful gear. By providing an equal limit for the progression of all characters, the level cap allows for competitive and balanced gameplay in both PvE and PvP.
Note that character level is limited by which expansions the player has purchased, with only players who have purchased the latest expansion able to reach the current level cap. As of early 2015, players with the standard game are able to reach level 90. The free Starter Edition of the game has a level cap of 20.
The game is not over at the cap
When the level cap is reached, players who are used to the leveling game sometimes have difficulty working out how to continue their adventures. After reaching the cap, however, is where the game developers are hardest at work for the players.
Once characters reach the level cap, gameplay turns from leveling to the end-game. This represents the culmination of the leveling process and the beginning of the deeper challenges awaiting max-level characters. While play prior to this point is oriented around accumulating experience and gaining new skills, the end-game represents the polished 'final destination' for players, at which characters are fully developed and ready to tackle the biggest challenges in the game, or to relax and make their own adventure.
For a guide, see End-game.
World of Warcraft originally had a level cap of level 60, but as expansions are released, the level cap is increased by 5 or commonly 10.