Guild of Adventurers

When you first create a character and join the game you will find yourself in the Guild of Adventurers.

The Guild of Adventurers complex is where you will learn to play the game by completing some tutorial quests.
The first quest is inside the Adventurers Guilds complex, enter the complex and go downstairs to talk to Thacknor the Dwarf.
Progressing through the tutorial quests will teach you a lot about the game. You will be rewarded with various weapons and potions, harvesting and crafting professions, plus gold and experience.
Completing all the tutorial quests will empower you with the capability to build your own house.

All you can achieve via the tutorial quests can be gained in other ways, but the tutorials are recommended.

Members of the Guild of Adventurers can learn quite a few skills and spells, but the more advanced skills and spells are only available from the higher guilds.
Higher guilds include the Guild of Warriors, the Guild of Mages, the Guild of Priests, the Guild of Rogues, and others. To join a higher guild you need to explore Keltrath and complete the required quests.

Joining a higher guild is not essential. You can remain in the Guild of Adventurers while still progressing in the game and helping new Guild of Adventurers members.