While there are no "classes", Avatars can choose to join Orders, which are basically character archetypes or templates. Orders make it easy for those who are not experienced role players to begin play. So while there is no "sailor" class, you can join a "Mariner" order, for example, where the major Ability is Waterfaring. The better you get at Waterfaring, the higher "Rank" you can achieve in the order. Orders make it easy for new players to play a character concept they are comfortable with -- for example, a player that likes to play warrior-type classes in other games might choose to join the "Soldier" order (where the major Ability is "Weapons"). Each Order has a specific set of four Abilities that will need to be obtained to reach the higher Ranks of the Order. For example, the Forester Order's four required Abilities are Hunt, Weapons, Archery, and Rustic.
Examples of other Orders include Ecclesiastic (priests and clergy), Jongleurs (wandering entertainers), Mages, Nobles, Rogues, Outlaws, and Warlocks (necromancers).
However, you do not need to join an order. You can choose to become an "Unordered" Avatar, and create a custom character based on the abilities you choose yourself. If you follow your own road as an unordered avatar, you can be a truly unique character in the world.
While there is no "alignment" in this game, there is the concept of "Repute". You get Repute for "brave and remarkable deeds". You get Dark Repute for "daring and desperate deeds that serve an overall beneficial end, but are also to some degree destructive, savage, [and] deal death to the undeserving." Finally, you gain Disrepute for "especially ignoble, vile, and terrible acts." You can learn more about the various forms of Repute in this post.
You gain Merits for good play -- merits are a form of experience. You can also gain Demerits for bad play -- these cancel out Merits.
There are a number of races in the LA -- besides Humans, you can choose to be a Dwarf, a Gnome, a Kobold, an Orc, a Wylf (elf), and some more unique races such as Veshoge, Trollkin, Oaf, and Ilf. Some races have subclasses as well.
Non-human Avatars can have Knacks (minor advantages), or Quirks (minor disadvantages).