The Similarity Report is a flexible document that provides a summary of matching or similar text in submitted work compared against a huge database of internet sources, journals, and previously submitted work, allowing students and instructors to review matches between a submitted work and the database scanned by Turnitin.
Therefore, the Turnitin Similarity Report does not define whether a student's work is plagiarized. The instructor responsible for the course - as a subject-matter expert - has a duty to exercise academic judgment on the work that is submitted to Turnitin for their classes.
The percentage that is returned on a student's submission (similarity score) defines how much of that material matches other material in the database, it is not a marker as to whether a student has or has not plagiarized.
Matches will be displayed to material that has been correctly cited and used, which is where the instructor's academic judgment must come into play.
Guidance on how to interpret the Similarity Report and its similarity score is available in our Help Guides.