Government of Australia knows that it is important to help families who come from other countries to reunite in Australia. If you are a Australian citizen or a permanent resident, you are able to sponsor your spouse, common-law partner, conjugal partner, dependent child (including adopted child) or other eligible relative (such as a parent or grandparents etc.) to become a permanent resident in Australia. If you sponsor your relative to come to Australia, you are responsible for supporting them financially after arrival in Australia. You also must make sure that your relative does not need to seek financial assistance from the government of Australia.
There are two different way to process a sponsorship application. First is for sponsoring your spouse, conjugal or common-law partner and/or dependent children. Other process is used to sponsor eligible family members, such as Parents, grandparents etc.
References: Citizenship and Immigration Australia / Immigration and Refugee Board