Can anyone please explain what is TR Visa? Why and when it is required?

TR visa means Temporary visa for international students who wants to stay in Australia to live, to study or to work after completion of their studies.

To be eligible to apply for the temporary graduate visa (subclass 485) you must

1. be under 50 years of age
2. hold an eligible visa and have a recent qualification in a CRICOS-registered course
3. meet additional requirements of the relevant stream

Students can opt this visa under two streams i.e. Graduate Work stream and Post-Study Work stream.

Graduate work stream is for the international students who have recently graduated with skills and qualifications that are relevant to specific occupations Australia needs. It lets you live, study and work in Australia temporarily.

Post-Study Work stream is for international students who have recently graduated with a degree from an Australian institution. It lets you live, work and study in Australia, temporarily.

More details can be found on website of Department of Home Affairs.