Shouting is a noisy method of communicating. If you're in a city, you can shout and everyone within a certain radius who doesn't have shout earmuffed will be able to hear you.
In cities, the radius seems to be about fifteen rooms, although this may vary. In terrains, you cannot hear someone shouting even from the next room, since rooms are supposedly a mile apart.
It's possible that the distance from which you can hear someone shouting varies from player to player, or that some locations (such as the roof of the Drum) are better for hearing shouts. It seems to be possible to be able to hear someone shouting when they can't hear you.
- Town criers use shouting to spread their messages.
- If you shout, "Lag!" in Ankh-Morpork, the Lag will shout back and soul at you. If you do this in Bes Pelargic, the Laggy-san will shout back and soul at you... but you'll also get disconnected and possibly get stat damage, as though you'd shouted eight.
- Shouting "eight" or "8" will disconnect you (and may cause you to have damaged stats when you log back on). The same happens when shouting "LAG".
- A'Tuin shouts a message before Offler starts the reboot countdown.
- When someone dies for the last time, there's a message you get if you don't have shout earmuffed (although it doesn't look like a shout).