Turnitin is an online plagiarism detection tool that allows students to submit assignments electronically and receives originality reports. It can be used for formative feedback by setting up Turnitin assignments on the module page. Issues around online submission and context need to be considered when using Turnitin. The document provides instructions on how to create a Turnitin assignment, set options like due dates and originality reports, and how students will access submitted assignments and feedback.