Checking in Overseas
Australia has a universal visa system. This means that all people travelling to Australia (except Australian citizens) require a valid visa or authority to enter Australia. This ensures that the department is able to facilitate the entry of people on arrival.
When you arrive at the check-in counter overseas, you will need to present your travel documents to airline staff. Airline staff will then check your details against immigration data systems to ensure that you have a valid visa or authority to enter Australia.
If you do not hold the correct documentation or visa/authority to enter Australia, the airline may refuse to allow you to board the aeroplane.
Your travel documents may also be checked prior to boarding the plane as an additional border security measure.
Further information
Further information is available on checking in overseas.
See:
Travel Documents for Entry to Australia
Visas & Immigration