The online system where tutors mark assignments and documents are verified as original work.
Turnitin is an application that checks documents for unoriginal content. After your work is submitted, tutors use the system for commenting on work and awarding marks.
If your tutor uses Turnitin you will be invited to submit your work through Moodle which will automatically send it to Turnitin for checking.
For more information about Turnitin, check out the Moodle support system (login required).