Turnstile

A turnstile, also called a baffle gate, is a type of gate. It only allows one person to pass at a time. It can also be made so as to make one-way traffic of people. It can also make passage only to people who put in a coin, a ticket, a pass, or similar. A turnstile can be used for paid access (sometimes called a faregate when used for this). For example, it can be used in public transport as a ticket barrier or at a pay toilet. 
Turnstiles are used at a variety of places. This includes stadiums, amusement parks, museums, and mass transit stations.