Factions in Stronghold Kingdoms are the equivalent to Guilds, in other online games.
A coming together of up to 40 people, united with similar aims. All Factions can have a maximum of 40 members, 1 leader and 5 officers.
The Officers and Leaders determine those 5 people via internal votes, that only they can see; it can of course be openly discussed with the Factions members via any means. Most use the inbuilt Faction forums and/or chat to do so, allowing a multitude of communication methods for you all.