You know how in Skyrim, or any other TES game, you level up skills to level up? Badaboom. Using a weapon your level gives bonuses. To level up you need exp in skills, then to go to a trainer, and buy the desired expertise tree. The point of the game is to level a lot, PvP after you're leveled well, and to survive. Like most MMOs. Like WoW, you buy levels, and like TES, you level certain aspects to level yourself.