On The Forge, each game/server is a subdomain of The Forge. That is to say, each game is encompassed by The Forge’s domain name.
We allow each user to set a custom subdomain for their game/server. If they are at the Game Master tier or have our Game Manager feature disabled, a user can set a single subdomain URL for their entire hosted Foundry VTT server. If a user has Game Manager enabled (a feature available at our Story Teller and higher tiers), they have a subdomain for each game.
In layman’s terms, its basically a unique URL you set for your Foundry VTT games/server. This lets you easily link to the game, as well as link your game to others.
For both infrastructural and security reasons, we cannot support DNS A or CNAME records on our service. If you wish to link your players to The Forge via a custom domain of your own, we recommend a simple redirect (HTTP 301 response). Users can also set up a URI record directly, to redirect from a custom domain toward their game’s subdomain.