ABTA - the Association of British Travel Agents.
Add-on - A selection, typically at an increased price, added to a travel reservation.
Adjoining rooms - Bordering hotel rooms that do not share a common door.
Advance purchase requirement - Ticket must be purchased a minimum number of days before the flight departs.
Airport code - the three digit code which is unique to a specific airport. eg. LHR for Heathrow.
APEX - Advance Purchase Excursion (fare). These are usually the cheapest tickets the passenger can get though they are restricted in number.
ARC - The Airlines Reporting Corporation - is responsible for supervising payments from travel agencies to airlines along with the manner in which tickets are issued to consumers.
Airport access fee - A fee paid to the airport authority by car rental companies for the use of shuttle vehicles. This often appears in customer’s car rental bills. 
Availability - The total number of seats allowed to be sold at a particular rate.

Back-to-back ticketing – when the passenger combines two return trips with opposite start and destination points but uses only a single segment from each to achieve a lower overall fare.
Baggage allowance – the weight of the luggage the airline allows the traveller to check-in.
Base fare - The cost of an airfare prior to addition of fees, taxes or surcharges. 
Blackout dates - Specific dates in which special fares or promotions do not apply. Typically exist around holidays or special events. 
Blocked space - Seats reserved to be sold to third party companies at a discounted group rate. 
Boarding pass - A ticket issued at airport check-in that authorizes airplane boarding.
Budget airlines - these are short-haul flights at bargain prices but with occasional drawbacks. Usually the flights are from secondary airports which could be miles from your ultimate destination. Food and drink is often not included in the price.
Bulk contract - An agreement whereby an airline sells large blocks of seats at a discount for resale by a third party. 
Bulk fare - A reduced fare for purchases of a large number of tickets.
Bumped - this means that the number of seats on the flight has been oversold.
Business class - While amenities vary based on the airline, business class generally falls between first class and coach.

Cancellation penalty - A fee to charged to customers that cancel flights after booking reservations. Fees typically vary based on the agency or carrier.
Capacity-controlled fares - a certain number of seats on a flight to which a cheaper price has been allocated. This percentage changes depending on how quickly the seats are sold.
Carrier - the organisation responsible for transporting passengers or goods – in terms of flights, this will be the airline.
Charter - an aircraft which is used by a specific group be it customers of a particular holiday company or an individual party.
Check-in - the time before departure when your luggage goes onto the airline and boarding cards are issued. 
City pair - the chosen cities for departure and arrival.
Commission - A small fee that a travel agency or services adds to the total fee in order to make money.
Companion fare - usually part of a promotion where another ticket may be purchased at a lower rate than the original fare. Normally this is dependent on the two passengers travelling together.
Consolidator - A business that has contracts with airlines to sell tickets in bulk, generally at a discounted rate. 
Construction tickets – term given to two single tickets bought to make up a return flight.
Corporate agency - A travel agency that usually caters to medium-large sized businesses. 
Coupon - this is part of the ticket that the passenger hands over at check-in and also contains the contract of carriage.

Direct flights – a flight where the passenger does not need to change planes but the aircraft may stop en-route.
Discounted tickets – by shopping around you will often be able to find agents selling cheaper tickets than advertised by the airlines but usually you will subject to various restrictions. 
Domestic fare - An additional fare added to national flights.

Electronic ticket - A paperless ticket that allows travelers to fly with only a photo ID. Commonly referred to as “E-ticket’s”, they cannot be lost or stolen because it is an electronic reservation.
ETA – Estimated Time of Arrival
EST – Eastern Standard Time (GMT-05 hours)
Excess baggage – checked-in luggage which exceeds the weight of the Baggage allowance. If you are only just over then you might be lucky but be warned that payments on excess weight can be very expensive.
Exclusive fare- Discounted airfares offered by travel consolidators. 

Fare basis (code) - The code that determines the price of an airline ticket. 
First class - The class which offers the most premium service. Enhanced seating, meal selection, and drink offerings staples of this services.

Global distribution system (GDS) - An international computer reservation system that accesses many databases of suppliers, airlines, etc. in different countries, such as Sabr
Greenwich Mean Time (GMT) – the international time standard

Hidden city faring – this is when a passenger organises their flights to achieve a final destination that is different from their official itinerary in order to get a lower fare. 
Hub - A city in which an airline has a major presence. Often, it is the city in which the airline was formed. 

IATA – International Air Transport Association
IATAN - International Airlines Travel Agent Network - Administers the IATAN card, the only widely accepted form of legitimate travel agent identification.
Illegal connection – flights that are booked where the time between landing and taking off on the next flight does not adhere to the legal minimum requirements.  
Indirect flights – this means the passenger will have to leave the plane at some stage during the journey – either so that it can refuel or possibly so that the traveller can change planes in order to complete the trip.
Interline connection - A trip with a connection flight from a different airline.

Joint fare – an arrangement between carriers to charge special rates when a passenger uses their respective airlines.

Land arrangements - All non-flying reservations upon arrival such as car rental, hotel, and tourist reservations.
Layover - The period of time spent between connecting flights. 
LDW - loss damage waiver - Supplementary car rental insurance that covers theft, vandalism, and accident damage.
Leisure travel - Usually signifies traveling for relaxation, vacation, or to visit friends/family.
Limited service hotel - A hotel without a restaurant on the premises. 
Long haul flight – a flight of considerable distance and time – often with the passengers suffering some significant jet-lag along the way.
Lowest available fare - The most inexpensive flight currently available

Maximum stay - The longest period of time a traveler can stay at a particular destination and still qualify for the promotion or discounted fare.
Minimum connect time - The shortest time required in order to successfully transfer to a connecting flight. It is recommended to select a connecting flight that exceeds the minimum connection time. 
Modified American plan (MAP) - Meal plan that includes two daily meals, usually breakfast and dinner
Multi-hop or Multi-leg – a journey where the passenger does not just fly between two airports to reach their final destination but where they stop en-route any number of times and perhaps spend time in each of the destinations.

Net fare, net rate- Implies the commission has already been added to the price of the fare.
No show - A traveler that doesn’t appear for their flight, hotel, or car rental reservation.
Non-refundable- A ticket in which no money will be returned if the customer no longer intends to use the ticket.
Non-transferable - A ticket that can only be used by the person who was originally scheduled to fly at the time of purchase. 
Nonstop - A flight that travels directly to its destination without connections or layovers

Occupancy rate - The proportion of reservations expected during any given period.
Offline connection - A connection that requires switching to both a new aircraft and carrier.
Off-peak - A less expensive time to travel as result of lower consumer volume during these periods.
Operator - Any company that provides any transportation service. Not just limited to flights, it also includes trains, buses, and cruise ships.
Overbooking - When a carrier books more reservations than available seats

Passenger facility charge (PFC) - an additional fee for the use of the airport.
Passenger name record (PNR) - The official name of one's reservation in a computer reservation system (CRS).
PDT – Pacific Daylight Time (GMT-08 hours)
Penalty fare – the amount the passenger has to pay in order to make a change to the travel arrangements or cancel the ticket once it has been issued
Personal effects coverage - Additional car rental insurance covering loss of personal property from the rented vehicle.
Point-to-point - Refers to the fares between two cities.
Published fare - A fare immediately offered for purchase by the airline. This does not include heavily discounted flights usually offered to consolidaters.

Rack rate - The price of a hotel prior to discount.
Reconfirm - to double-check a reservation.
Record locator - The number assigned to a reservation in the airlines number. This number is unique, as it will never be assigned again.
Red-eye flight - A flight in which the travel takes place between the hours of 9pm and 7am.
Reissue - When a new ticket is issued as a result of a change of plans. This can often require fees or penalties from the airport. 
Restricted to airport check-in – seating allocation and boarding passes which can only be assigned to the passenger at the airport.
Round trip - Two flights: the destination flight and its return trip

Sabre® - The world’s largest travel reservation system.
Saturday night stay - In order to receive a specialty fare, a Saturday stay over is sometimes required. 
Segment – an identifiable leg or part of a journey. Usually defined by departure and arrival destinations.
Scheduled carrier - An airline that offers regularly scheduled flights between destinations.
Special fare - Any fare that deviates from normal pricing (typically discounted).
Shoulder season - The period of time between busy and quiet seasons in which prices are typically at a midpoint.
Situated In, Ticketed In (SITI) – where you buy the ticket from the country you are leaving. 
Situated Out, Ticketed Out (SOTO) – where the ticket is bought from your destination country.
Split ticketing – when you travel using two single tickets instead of a return in order to obtain a lower fare
Standby – this is if a passenger holds a ticket that does not automatically guarantee a reserved seat means instead that they are waiting for availability.
Stopover – an overnight stay (or possibly longer) at a location en-route to your final destination. This is usually done to break up a very long journey.
Suite - A hotel room that usually offers a living room and kitchenette in addition to the bedroom.
Supplier - A company that offer travel services to the general public
Surface sector – the distance between departure airports using an open-jaw ticket. The customer is responsible for organising the travel between the two points of departure.

Through passenger - A passenger who remains on the plane at a connecting stop on the way to his/her final destination.
Ticket stock - Blank airline tickets.
Ticket issuance – purchasing tickets that have previously been reserved.
Travel agent - An individual or company that sell travel services on a commission basis.
Travel agency- Usually used in the travel industry to refer to an ARC-appointed storefront retailer.

Unlimited mileage - Signifies there are no mileage restrictions for renters.
Unrestricted fare - An airfare with no limitations. It is typically refundable and has no blackout days

Waiver - A written acknowledgement that a passenger has declined something.
Window of convenience – the traveller’s ideal departure or arrival time – plus or minus two hours.