# Travel

Airport and airline codes, flight numbers, cabin classes and bookings.

## Types

| Type | What it is |
|---|---|
| [`IataAirport`](/docs/types/type-iata-airport.md) | An airport's three-letter code, as tickets print it: `LHR`. |
| [`IcaoAirport`](/docs/types/type-icao-airport.md) | An airport's four-letter code, as air traffic control uses it: `EGLL`. |
| [`IataAirline`](/docs/types/type-iata-airline.md) | An airline's two-character code: `BA`, `U2`. |
| [`FlightNumber`](/docs/types/type-flight-number.md) | A flight's code: `BA123`. |
| [`CabinClass`](/docs/types/type-cabin-class.md) | The cabin a seat is sold in: `economy`, `premium_economy`, `business` or `first`. |
| [`BookingReference`](/docs/types/type-booking-reference.md) | A booking's six-character reference: `X7K9QZ`. |