Unlike previous versions of the series, Fallout 76 is a fully online production. This means that while you’re wandering around the world you’ll find other players. They may be neutral for you and indifferently pass by your character, but it may happen that a player attacks you or offers you an option to start a co-op team.
Fallout 76 How you can join a team?
Joining a team is very easy. You can be invited to join the team at any time by the group leader – then a message and a key combination will appear on the screen, which must be pressed to accept the invitation. If you join a team, a list of all group members will appear on the right hand side of the screen.
You can also become a team leader yourself and invite other players to join the team. Simply approach any player and select the “Invite to team” option. The selected player will receive an invitation and if they accept it, you will become the team leader. As a team leader, you can throw other players out of the team (and invite others to join you) as well as promote someone to the team leader.