When you fly on a commercial airline, there are often last minute passengers who fly on a status known as "stand by." These customers are able to obtain air travel a fraction of the price you normally pay as a reserved seated customer. The risk to them is that they might not get on the plane if it is sold out, and they face the inconvenience of not knowing if or when they might get to where they need to go, and they are unable to check baggage or choose seating preference. In exchange for this inconvenience and risk, they receive a deep discount.

Do you think their presence on the flight increases or decreases your ticket cost? What is the economic term for this practice by airlines?