MHW: This is the Session ID and this is how you use it

Monster Hunter World is designed for multiplayer sessions for up to four players. These have various ways of finding each other in the game and this includes the session ID. We explain what it is.

Session ID also lets you join private sessions and invisible friends.

Especially in Iceborne, hunting with multiple players is noticeably easier. Session ID is a tool to organize multiplayer sessions.

MHW: How Session ID works

Once a player starts the game, he has two options: Either, he joins a game or he creates his own game. Either way, each running game is defined as a session and consequently gets an individual ID. This numerical code is unique and thus serves to ensure proper assignment. This means:

• If you get a friend's session ID, you can use it to join his game.
• Inversely, you can copy & paste your own session ID to your friends so that they show up in your game.
• The session ID is particularly handy in some cases. For example, when someone is invisible on Steam, so that his MHW game does not appear in the overview of friends sessions. With his session ID, you can still join the game.
• Also private sessions are not visible and can only be entered by invitation or session ID.

You can find your session ID by opening the menu and selecting "Communication" there. In the list you will see the option to copy the session ID and then you can simply paste it into a chat program.