All players on the mainland can create their own party and invite other players to it. Players in a party can attack and kill each other (on PVP servers) without the hits counting as unjustified. To create your own party, write #party
in the Main chat channel.
To invite players into your party, right click inside the party window and choose "Invite Player". The invited player must accept the invitation by entering #join [yourname]
in the Main chat channel. You can also kick members out of the party or leave the party by right clicking on the party window and choosing the desired action. If the party leader leaves the party or logs out, the next player in the party list is promoted to the party leader position. All the players in the same party as you are marked with a blueish plus-sign near their character's head.
When hunting in a party the experience is distributed evenly across all party members based on their level. For example, if a level 10 and a level 20 hunt in a party, the level 10 receives about 33% of the total experience and the level 20 player receives about 66%. The total experience gained in a party is increased by 10% per party member, however, the maximum increase is 60% (6 party members).