Turnitin identifies similarities between language used in a paper submitted to works in their database. This database contains articles (Academic Journals & Magazines), previously submitted papers (other student papers & previous work from the student submitting the paper), and websites. Turnitin then generates a Similarity Report. This report is also sometimes referred to as an Originality Report. A percentage of matching words are provided in the report as a Similarity Score.
Turnitin only detects similarities in a paper that has been submitted. These similarities DO NOT necessarily indicate plagiarism. Remember that quotes and citations used in a student’s paper will contribute to their Similarity Score.