The skill system in The Elder Scrolls Online is different than other MMOs out there. You'll choose between the game's four classes (Dragonknight, Sorcerer, Templar, and the Nightblade), and level up abilities the more you use them. Each class can equip specific skills which can be earned to build up your character's combat identity. For instance, Nightblades are much like the classic rogue with a pretty even split between poison-style skills, stealth, and straight-up assassination.
Choosing the Dragonknight class has a combination of damage-dealing, damage absorbing, and stealth abilities; the Sorcerer commands dark magic and summons; and the Templar has various aggressive DPS skills and healing abilities to mix and match. Depending on which skills you choose can produce very different feeling attack combinations. Plus, weapons level as you use them, granting you skills respective to the weapon type, which include dual-wielding, two-handers, magic staffs, and more. On top of that, there are multiple skill trees to unlock linked to the guilds you join (like TES's Mage's Guild and Fighter's guild), the race you belong to, your alliance, and even some mythological curses you might become infected with. And yes, we're talking about vampirism and lycanthropy.