Groups are characters which have banded together under a leader. The groups menu can be accessed anywhere at any time, and groups have no cap on the number of members. There are different group types with their own purposes, but generally groups are for characters who are either on their own without town allegiance, or are rebelling against a town. It's also useful for parents to keep their children organized, as all adult members of a group can drag other members. Children are also allowed to create their own groups.
To create a group you select the menu and choose your group type. Once your group is created, from the same menu you can start adding people to your group. The list of people to select from is based on who is present in the same area with you at the time. Adding people to a group requires their consent, so they will be added once they accept your request. You can also select an heir from this menu once you have some members in your group to choose from. This heir will be able to ensure the group remains intact even if the leader becomes incapable or dies. If both the leader and heir become incapable/die then the group will be disbanded automatically, as there is no one to lead it.
Groups were created to rival guards and to be a convenient way to travel, but they have their own set of restrictions. You can only be in one group at a time (joining another group when you are already in one will just set the newest group as your current one). You cannot be a guard and in a group at the same time and cannot change a group's type after creation. If you want to change the type of group you are leading, you will have to disband the current one first and then ask all the old members to join it again (this is on purpose to avoid abuse). Only militant group types will automatically defend their members from attacks initiated by others, but unlike guards this will not initiate an ongoing attack over time. Those can only be initiated by the leader of a militant group. You cannot add characters to your group if they're on your own account.
When you join a group you are essentially allowing the leader to make all the decisions about where you go and potentially what you do - consider it a sign of trust to agree to a grouping. Deviating from the orders of a leader, for example turning around on a road while following a group, will break you from the group completely because you are using free will.
A travelling group is created only for the purpose of being able to travel together without all players having to be online at the same time to coordinate movement. A travelling group will follow it's leader down roads to different map tiles. The speed of the entire group will be determined by the slowest member of their group. The leader should ensure everyone is mounted or in their vehicles before leaving the tile if they want to maximize the speed of their group. If the leader leaves a tile when all their members are not outside, the members left behind will be abandoned from the group automatically. Travel groups do not automatically defend their members as a group.
Example: If three people in a travel group are following a leader who has 3 mounts with vehicles attached, if they each get in a vehicle they will all travel in their respective vehicles, following the leader when they direct the travel. The leader must direct the travel in order for this to occur.
A militant group is the antithesis to guards, and can be used in a similar way. Characters in militant groups follow all the same rules and limitations as characters not in groups where combat is concerned: 1 hour delay per victim is still required in order for them to retaliate. Leaders of these groups can order their inactive (offline for more than 15 minutes) members to attack a specific person, continually until incapable (active members will have to manually select attacks). When a group member is attacked the entire group will defend their member by returning the blows to the attacker, within their limit, and only if they're inactive. Militant groups will also automatically travel with their leader just like a travelling group, however an important distinction is that militant group members cannot work on projects for the duration of their membership.