If you are in a relationship with an Australian Citizen or Australian Permanent Resident, or Eligible New Zealand Citizen then you can consider applying for a Partner (a.k.a. Spouse) Visa.
To be eligible to apply for a Partner Visa the applicant must be able to prove one of the following;
1.) They are legally married to an Australian citizen or permanent resident or eligible New Zealand citizen - Partner (Marriage) Visa
2.) They have been in a de facto relationship (living together like a married couple) with an Australian citizen or permanent resident, or eligible New Zealand citizen, for a period of at least 12 months immediately preceding lodgement of the application (unless they have entered in to a formal Civil Union as recognised in Queensland, Australian Capital Territory, New South Wales, Victoria or Tasmania only) - Partner (De Facto) Visa
3.) They are formally engaged to be married to an Australian citizen or permanent resident or eligible New Zealand citizen, have personally met and are free to marry that person - Fiancé Visa
This means that most Partner Visa holders are temporary residents for two years, and then go through second stage processing which is when the permanent visa is granted. The two step process is DIBP's way of safeguarding against people who are not genuine and you should also be aware that if the relationship breaks down before the two years is up the permanent application may not be approved unless certain circumstances apply.
Fiancé Visas go through a three step process - the first part is lodged offshore and once granted the applicant has around nine months to enter Australia, marry their sponsor and lodge the Partner (Marriage) visa.
All partner applications are judged on the genuineness of the relationship and you will need to be able to provide documents to show that you are in a long term, committed relationship with each other.
The 12 month requirement for De Facto visas can be waived if you can provide evidence that your relationship has been formally registered as a 'Civil Union' or 'Registered Relationship' in Queensland, New South Wales, Tasmania, Victoria or the Australian Capital Territory. Please refer to your local Registry of Births, Deaths and Marriages for further information.
Applicants who lodge on the basis of a Civil Union relationship or Marriage would ideally need to show at least six months of a committed relationship, including evidence of a joint household. Fiancé visa applicants are not required to show that they have been living together, but must be able to show that they have personally met or seen each other since they turned 18, and that there is at least six months of a committed relationship.
If you have only been in a relationship for a short time, then any application you lodge will most likely be rejected.
Partner visa applications can be lodged in Australia or overseas. The Fiancé visa must be lodged overseas at the Embassy responsible for the applicant's usual country of residence.