Valheim's world is huge, and coordinating your position with other players can be pretty difficult. To avoid losing track of each other and where you are, it's important to know how to mark your position for other players to see. Not to worry, we'll show you here how to ping the map and mark yourself.
How to Ping the Map in Valheim
To ping the map in Valheim, you can actually do it fairly easily by opening the map and clicking on a specific location with the middle mouse button (assuming that's what you have set up in the settings). That'll mark the map for everybody to see, a blue ring with your name in it. However, the ping doesn't last for more than a couple of seconds, so it's more useful as a general indicator than as a pin in the map.
It's possible that a new system will be added in the future, but for now this is the only way you can mark locations to other players on the map. Not to mention that abusing it too much is likely to get very annoying fast, so be reasonable about it, otherwise the server admin might ban you.
Of course, this assumes that you're playing co-op with friends, and if you're wondering how to do that, check out how to play Valheim with friends here! Or if you're looking for a challenge to share, here's where to find the first boss fight and how to beat it.