Many airlines use nearly all letters of the alphabet to allow finer yield management. Nevertheless, certain booking codes have retained the same meaning across most airlines: Common Airline Classes of Service Codes F - First Class, J - Business Class, W - Premium Economy, Y - Economy/Coach.

In the airline industry, Economy Class is represented by a variety of single-letter "fare codes" that indicate the specific type of ticket purchased. The most universal letter for standard Economy is "Y", which typically signifies a "full-fare" economy ticket that is flexible and refundable. Other common letters used across major airlines include B, M, H, Q, K, L, V, and S. Each of these letters represents a different "bucket" of pricing; for example, "L" and "V" are often used for deeply discounted or promotional fares that have the most restrictions. "O" and "U" are frequently used for frequent flyer award tickets. If you see the letter "E", it often denotes Basic Economy, which is the most restrictive tier with no seat assignments or changes. Understanding these codes is useful for frequent flyers because certain letters earn more miles or are easier to upgrade. While "Y" is the king of the back of the bus, the letter on your boarding pass determines everything from your board group to how many points you'll see in your account after the flight.