In most cases, you'll be able to check in directly on your airline's website or mobile app.
You will need your airline reference for this. You can find your airline reference on your itinerary beside your flight details.
If you have booked a codeshare flight you will need to check in with the operating carrier.
A codeshare flight is a flight that is booked on one airline and is operated by another. For example you may have booked a Qantas flight and this is operated by an Emirates aircraft.
The operated carrier will show on your itinerary.
If you have not been able to pre-select your seats due to your fare type, you can do this when you check in.
If you require special assistance have been requested you may need to check-in at the airport.
Unaccompanied minor bookings will need to check-in at the airport