Fare evasion or fare dodging, fare violation, rarely called ticket evasion, is the act of travelling on public transport without paying by deliberately not purchasing a required ticket to travel (having had the chance to do so). It is a problem in many parts of the world, and revenue protection officers and ticket barriers, manned or automatic, are in place to ensure only those with valid tickets may access the transport. The term fare avoidance is sometimes used as a euphemistic synonym and sometimes used to refer to the lawful use of much cheaper tickets.