The admission order office is responsible for allocating tickets for members of the public to watch the proceedings of the Commons from the Public Gallery.
It is situated next to the central lobby in the Houses of Parliament.
Only a limited number of tickets are available.
Popular events - such as prime ministers questions - and topical debates often produce long queues of people outside Parliament waiting for tickets.
MPs are allocated a pair of tickets for the Public Gallery on a rota basis (every nine sitting days, excluding Fridays) which they can make available in advance to constituents who request them.