If you are undertaking any nationally recognised training you will need to have a USI from 1st January 2015. The USI is a file number that will link your person details and your vocational education & training (VET) records. Details of all VET courses that you complete will be collated and held in a national registry.
It is free and easy for you to create your own USI online.
Under the legislation training organisations can only issue certification when they have received your USI.