Agents are also paid bonuses as part of annual rebate deals with airlines so they will drop their margins on routes with a certain carrier to ensure they meet targets if necessary.
The travel trade sells "early bird" fares for the next northern hemisphere summer, traditionally in October and November but as early as August.
This is the first release of the "season" and generally has the greatest level of availability. Any fares or packages left from this period will then go on sale again in February.
People always think something better will come out and sometimes it does but the advantage in booking early is that you can get better access to the days or weeks you want to travel.
Helloworld's general manager of marketing, David Libeau, said by waiting until the last minute there were sometimes better prices as airlines look to close out their capacity but people could be compromised by less choice of when to travel.
"People always think something better will come out and sometimes it does but the advantage in booking early is that you can get better access to the days or weeks you want to travel."
In an air fare guide, Flight Centre says while there are last-minute deals, booking domestic flights 21 days or more from departure or international flights two months in advance will often result in greater saving.
World events, school holidays and competition between airlines will affect the price of your seat.
Airlines manage their inventory using complex algorithms that fix different prices, rules and restrictions to particular booking classes to ensure all flights are as close to full as possible.
Air fares will vary substantially within a cabin meaning the person sitting next to you is probably not paying the same price.
The Flight Centre guide says that airlines divide seats into "fare buckets" with a particular price and airfare rules attached. Once the lowest fare is sold a price from the next bucket is offered and so on until the flight is sold out.
Sometimes a fare bucket may not sell as quickly as the airline expects so a lower fare bucket may be added to boost bookings.
That means that travellers can pick up cheaper last-minute flights but these may result in a number of restrictions that go with them, including regarding the ability to change or cancel your ticket.
Cheap fares don't always come with extras that used to be part of a ticket such as a bag and food as airline ancillary revenue becomes increasingly important to most of them.
The biggest ancillary earners' revenue has grown from $2.9 billion to nearly $40b during the past 10 years.
