The subclass 300 is a temporary visa which allows people to come to Australia to marry their prospective spouse who is an Australian citizen or Australian permanent resident. You need to be sponsored by your prospective Australian spouse. This visa is granted for 9 months and the holder needs to marry their prospective spouse in Australia within this period. Once you marry the person you can apply for a subclass 820 temporary partner visa and later on get a subclass 801 permanent visa.
The applicant should have a genuine intention to marry their sponsor and live with them as husband and wife.
The applicant must be at least 18 years of age on the date of application.
The applicant should be of the opposite sex.
The applicant and the sponsor have met in person after both of you had turned 18. Meeting on internet through software like Skype are not regarded as meeting in person.
The applicant has to meet health and character requirements.
Once the applicant is granted the subclass 300 visa they must enter Australia and then marry their partner within the 9 month period. The marriage should not take place before entry into Australia. However, the visa holder may enter and then leave Australia and then get married overseas. After the marriage but before the subclass 300 visa expires partner can apply for partner provisional visa subclass 820. The permanent subclass 801 visa will be normally granted after 2 years if certain conditions are met.