Elden Ring is a huge game with so much to do. To balance this out, you are regularly met with tough areas and even stronger bosses. If you are looking for a little bit of help, summoning your friends is your best bet. Here's how multiplayer works in Elden Ring, including how to invite friends and play co-op.
How to play Co-op in Elden Ring
There are a few things you have to do before you can start co-op in Elden Ring. Outside of having a game and connection to the internet, you can set yourself online by clicking "log in" from the main menu. If this option isn't there, it seems likely that you are already online.
Elden Ring features both co-op and PVP modes but this will focus on friendly players. To play co-op, you either have to summon someone or get the ability to be summoned. If you want a co-op partner to join you, you have to use the Furlcalling Finger Remedy first. Not only can plenty of these be found but you can craft them with 2 Erdleaf Flowers.
After this, you will start to see summon signs on the ground. If it is gold, they are friendly. If it is red, they are not. Being summoned is a bit easier to do, as you gain the main item right at the start of the game. As you are leaving the start, you will spot a dead body holding the Tarnished's Furled Finger and Finger Severer. The finger lets you place down a sign and the Finger Severer send you or an ally home.
How to play with friends in Elden Ring
You can play with friends by using the exact same method but there's a slight caveat. Before you do this, go into the pause menu and go to the multiplayer tab. From here, you can create a password, which you then share with friends. Only those using the same password can join your world and vice versa.
This all being said, you likely shouldn't explore the world with a co-op partner as this stops your horse from being summonable. You are better off finding places to take out bosses and summoning them there.