There are many different non-player characters, or NPCs, that are controlled by the game instead of other players. They can greatly aid you in your travels throughout Sarnaut by providing various services. For example, there are merchants who buy and sell items, archetype trainers that offer various archetype-related services, many NPCs that offer quests for you to do, and numerous NPCs that you can kill.
Friendly and Neutral NPCs
Many NPCs are friendly or neutral. Friendly NPCs will not attack you and you won't be able to attack them. Neutral NPCs will not attack you, but you can sometimes attack them. However, attacking them will cause them to attack you in return. Friendly and neutral NPCs that you cannot attack can sometimes be interacted with in other ways. Many will talk to you or sell and buy items. You can interact with them by simply right-clicking on them.
There are also many hostile NPCs called monsters. They will attack you if you get too close to them. However, if you manage to kill a monster you will be rewarded with experience. Sometimes you can gather items from a monster's corpse as well. To gather the items you can right-click on the bag that appears near their corpse and then left-click on the items that appear.