Host screen
The host screen is the shared display, usually a TV, projector or laptop, that shows the game to everyone in the room while players use their own devices as controllers.
It does two jobs. It is the stage, showing the board, the questions, the arena or the drawings that everyone watches together. In many games it is also where the game actually runs, so the browser tab on the host screen keeps the state of the match and the phones send it their inputs. That is why the host device should stay awake, plugged in if possible, and on a good network.
Any screen with a web browser works for browser games. Smart TVs often have one built in. A laptop connected to a TV by an HDMI cable is the most reliable choice, and casting a browser tab from a phone or computer also works.
The best party games put the interesting parts on the host screen so people look at each other and the TV, not at their phones.
Bossfeed party games - open any game on a screen everyone can see to make it the host screen.