Boarding a flight for your holiday used to be a case of understanding if it was domestic or international... simple.

But things have changed.

And with the opening of a new international wing, Perth Airport has launched a $100,000 advertising campaign to remind people to check itineraries - to get the terminal right.

Perth now has four domestic and two international terminals while the introduction of the Dreamliner direct flight to London has seen the international wing built at the old domestic terminal.

This means, from this Saturday, all Qantas flights along with Jetstar's domestic services will operate from T3 and T4.

Camera Icon Confusion over terminals has increased since the opening of T2 in 2013.

T1 will be home for most other international flights, plus Virgin's interstate and some of its regional services.

And T2 will cater for those airlines that service the FIFO workforce, Tiger's interstate and Virgin's regional services.

As easy as that!

Camera Icon An Emirates 777 lifts off for Dubai from Perth Airport Credit: The West Australian

Well, apparently not, even for some frequent flyers, like Lorna Morris.

“Oh yes it's definitely, it is confusing, yes,” she said.

But Perth Airport’s CEO Kevin Brown believes it’s merely a matter of double-checking what terminal you’re flying from - rather than thinking domestic or international.

“The roads are well sign-posted approaching those four terminals but you have to be quite clear which terminal you're going to,” he said.

The ultimate aim, however, is to have all the terminals in the same place at T1, a project hoped to be completed by 2025.

“The terminals are all side-by-side, they effectively become one terminal and make it easier for people to transfer through,” Mr Brown added.

Until then... make sure you double check your ticket and terminal to avoid any last minute headaches.