Airline booking sites and boarding passes are full of terms that mean nothing until someone explains them once — and then they're obvious forever. Here's a working glossary of the ones that actually affect your trip.
Codeshare
A codeshare flight is operated by one airline but sold under another airline's flight number — you might book "Airline A 123" and actually fly on Airline B's aircraft and crew. It's common on partner routes and alliance networks. Codeshares aren't a problem, but always check which airline you'll actually check in with and what their baggage rules are, since they can differ from the airline you booked through.
Hub
A hub is an airport where an airline concentrates connecting traffic — flights are scheduled in banks that land and depart close together so passengers can connect efficiently. If you're comparing two travelers' routes to meet in the middle, a well-timed hub often produces more overlapping arrival windows than a smaller regional airport.
Layover vs. Connection vs. Stopover
- •Layover / connection: a stop between two flights on the same ticket, usually under 24 hours.
- •Stopover: a longer, often deliberate break in a journey — sometimes free, sometimes an add-on fare — that lets you leave the airport and explore.
- •Direct flight: keeps the same flight number but may stop en route (see below).
- •Nonstop flight: no stops at all, gate to gate.
Open Jaw
An open-jaw itinerary flies you into one city and out of a different one, skipping the return leg to your origin (or the outbound leg between two destinations). It's a useful trick for multi-city trips and for two travelers meeting in a city neither of them started in — fly in together, then each head home separately.
Interline vs. Codeshare Baggage
An interline agreement lets airlines check your bags through to a final destination even when you're switching carriers mid-journey, without you having to reclaim and recheck them. It's worth confirming before you book a self-connected itinerary across two separate airlines, since not every pair of carriers has one.
PNR
Your Passenger Name Record — the record locator or booking reference, usually 6 characters — is what airlines and airports use to pull up your reservation. Keep it handy for check-in, seat selection, and any changes.