An Australian employer may sponsor certain types of employees for permanent immigration to Australia. Employer sponsorship is available to workers who are either highly skilled (typically white collar) or who fill positions for which local employees are in short supply. Immediate family members of these employees also qualify for permanent immigration.
If you are currently in Australia, you may qualify for permanent immigration under Australia's refugee and humanitarian immigration as long as you meet the definition of a "refugee" under the United Nations Refugee Convention. If you are located outside of Australia, you may qualify (i) if you meet the above definition of a refugee, or (ii) if you live outside your home country and have a legitimate fear of returning based on a high likelihood of discrimination leading to serious violations of your human rights. If you live outside Australia, however, you will need to find an individual or organization to sponsor you.
Australian citizens and permanent residents as well as certain New Zealand citizens may sponsor their parents, children and domestic partners for immigration to Australia. The term "domestic partner" includes spouses, de facto partners, and even same-sex partners. Domestic partners enter Australia on a temporary visa but may apply for permanent residency after two years if the partnership is still ongoing.
You are eligible for immigration if you are a former resident of Australia who lived in Australia at least 18 years (half of that time as a permanent resident). If you have completed at least three months in the Australian Armed Forces before January 19, 1981, you will also be eligible under this status.
All immigrants to Australia must possess some form of valid travel documentation (a passport is usually required, but rules are often relaxed for refugees and special cases); a physical examination to establish that you are not a danger to public health, and police clearances from every place that you have resided for at least 12 months since you turned 16. In some cases you will also need to have a sponsor who promises in writing to provide for your support should you become destitute in Australia.
In order to become an Australian citizen you must legally reside in Australia for at least four years, and must live in Australia as a permanent resident for at least 12 months. You will have to demonstrate good character by producing police clearances for the time you have lived in Australia, and you will probably have to take a simple citizenship test requiring basic knowledge of Australia and rudimentary English language abilities. Keep in mind that numerous loopholes exist for the requirement to take the citizenship test.