From Asheron's Call Community Wiki
There are three social systems in Asheron's Call that players will use when grouping together.
Main article: Allegiance
An allegiance is a hierarchy of players who have sworn allegiance to other players, allowing them to share xp in exchange for items and help through the patron/vassal relationship.
The head of the allegiance is the monarch. A monarch will have up to 12 vassals. These vassals are also patrons to their own vassals, and so on. There also three ranks of Allegiance Officer that can be appointed by the monarch to help control the allegiance structure and make other changes.
Main article: Fellowship
A fellowship is a group of players who join together temporarily to have fun and earn xp while hunting or completing Quests. There are many benefits to being part of a fellowship such as optional xp/luminance/loot sharing, a bonus for xp sharing fellowships and interface improvements such as colored radar blips and a panel for player vitals.
Player Factions are groups established in the lore that players can join to take a bigger part in the game world.
Societies of Dereth
Main article: Societies of Dereth
Each Society has its own ideals and beliefs as to what should happen on Dereth and beyond. Players are given the chance to discover the principles of each Society and choose which group they want to join.
Once you have joined a joined a society you can begin earning Commendation Ribbons to gain access to tests to advance in society rank. Players in the top ranks gain entry to the Society Armor set and the landmasses Moarsman Isle and Freebooter Isle. You can also earn trade tokens to purchase various items such as society covers for Tailoring and writs that can be exchanged for keys to the society vaults.
The Land Control feature is also linked to the societies with each society attempting to gain control of various keeps.
The War of Blood and Shadow Factions
During the The War of Blood and Shadow story arc, factions were introduced to allow players to choose which side of the conflict they wanted to support. Unlike with the Societies of Dereth, these factions do not have much of an impact on gameplay and the main incentive to join one is the eventual access to the faction chapterhouse and the Red Rune Weapons set.