Points based visa for people who are assessed to have in-demand skills. Not tied to an employer. Very good for contractors but the points criteria are tough to meet. Your skills and experience must be on the Skilled Occupation List. As soon as you have this visa, you and and dependants included on your application can live as permanent residents of Australia. for a period of 5 years. You can eventually apply for citizenship. If you want to leave Australia and return provided you've spent enough time in Australia during that 5 years you can get a Subclass 155 Residents Return Visa.
You can check your points total on the website of the Australian Department of Immigration and Citizenship