A USI - Unique Student Identifier is a reference number made up of 10 numbers and letters that creates an online record of your training and qualifications attained in Australia.
If you are a new or continuing student undertaking nationally recognised training, you need a USI to receive your qualification or statement of attainment.
A USI is for life. You only have to create it once.
You may create one through this link if you don't have one yet: https://www.usi.gov.au/students/get-a-usi
Here's a link to how to create one: https://www.usi.gov.au/about-us/news/videos