Simply put, an airfare is the price a passenger pays in order to travel by air. The types of fares, rules and restrictions, taxes, etc., are all components that complicate the price involved for a passenger to fly from one place to another.
Fares are most often based on one-way or round-trip travel. Fares may be published, unpublished and/or negotiated fares (corporations, or government agencies/organizations may have fares negotiated with an airline at a lower rate). Unpublished fares are also known as consolidated fares and are offered by consolidators and bucket shops.

