Turnitin and iThenticate Similarity Detection

No. A 35% Similarity Index means that 35% of your text is similar to sources in the tool's database. This similarity may include quotations (which are legitimate if cited), references, boilerplate methods text, or actual plagiarism. The software cannot distinguish between these categories. You must review the detailed report to see what sources matched and whether those passages are properly quoted and cited. A 35% index could indicate serious plagiarism or could indicate legitimate academic writing with extensive quotations and citations.

No. If all flagged matching text includes quotation marks and citations, you have not plagiarized. The software flags similarity; proper citations and quotation marks indicate that similarity is legitimate. However, this highlights why instructors must review reports carefully rather than penalizing based on Similarity Index alone. If an instructor penalizes you for high similarity despite proper citations, this is unjust. Show your instructor the detailed report and your citations, and ask for clarification.

This indicates self-plagiarism or text recycling. When you quote yourself without quotation marks or reuse paragraphs from previous work, the software flags it as similar to a prior publication. This is appropriate—most publishers require disclosure of prior publications and prohibit republication without permission. If you are building on previous work, disclose it in your cover letter and potentially in your methods section (e.g., 'Based on our prior work [citation], we...'). Rewrite substantially or obtain permission from the publisher.

No. Software detects textual similarity, not all forms of plagiarism. Idea plagiarism (taking ideas without attribution), some forms of paraphrasing plagiarism, and translation plagiarism may not be caught. Low similarity does not mean clean work. Conversely, high similarity does not mean plagiarized work. Software provides partial information. Human expertise is required for a complete plagiarism assessment.