A waiting room is a building, or more commonly a part of a building where people sit or stand until the event they are waiting for occurs.
There are generally two types of waiting room. One is where individuals leave one at a time, for instance at a doctors surgery or outside a school headmasters office. The other is where people leave on mass such as those at train stations, bus stations, and airports. These two examples also highlight the difference between waiting rooms where you are asked to wait (private waiting room) and waiting rooms you can just enter at will (public waiting rooms).
Most waiting rooms contain seats for people so they do not have to stand. Some have adjacent toilets. It is not uncommon to find vending machines in public waiting rooms or books and magazines in private waiting rooms. In some countries there are special waiting rooms especially for those who have paid for them, for example at airports and railway stations. These will generally be less crowded and will have superior seating and more facilities.
The films Brief Encounter and The Terminal use waiting rooms as sets for a large part of their duration. They are used elsewhere in the arts to symbolise waiting in the general sense, to symbolise transition in life and for scenes of a romantic or sad nature.