First Class, those comfy seats at the very front of the plane where passengers start drinking champagne before the flight takes off, are actually subject to several fare classes. A full-fare First Class seat (F) or a Premium First Class seat (P) will cost you more that a discounted First Class seat (A) or a deeply-discounted First Class ticket (Y-UP, Z-UP, M-UP or Q-UP), which sells at just beyond full-fare economy prices.
Just behind First Class are the Business Class passengers, who can buy full-fare, unrestricted tickets (C, J) or obtain discounted fares, which may have more restrictions (D).
Airlines reserve most fare code letters for Coach Class, also known as Economy because these seats take up most of the space in the plane and can offer many fare prices. Common fare codes for unrestricted, refundable full fare tickets are S, Q, W and Y. Codes for discounted Coach fares are labeled as B, H, K, M and V.
Airlines use different "fare components," or structural breakdowns, to determine the price to charge. A Round Trip fare, commonly requested, starts with a passenger at point A and delivers him to point B, with or without layovers, and flies the same passenger from point B back to point A, again with optional layovers as determined by the airline. This is all calculated into a single fare that you, the passenger, sees.
Travel to your destination on a One Way fare if you're not planning on returning. While some carriers charge more if you don't book a Round Trip, others use only One Way fares to book tickets. You'll choose a fare for the outbound leg and one for the incoming leg of your trip.
A Circle Trip gives you multiple stopping places on a flight that eventually returns you to the place where you departed. These fares will charge you for three legs of the journey.
