The IELTS (International English Language Testing System) is a test intended to assess the English language ability of non-native speakers who wish to study or work in an English-speaking country.
The IELTS exam is made of four modules, or sections: Listening, Reading, Writing, and Speaking. The first three modules have to be taken together on the same exam date. The Speaking module though may be taken any time within seven days before or after the first three modules are completed.
For ELICOS (subclass 570) and vocational courses (subclass 572) IELTS might not be necessary. For university courses IELTS is required most of the time unless you are exempt. The pass mark depends on the course and institution and is normally between 6.0 and 7.5.