Turnitin, used via Moodle, is a platform for setting, receiving, marking and giving feedback on assignments. Turnitin accepts a range of file formats. For text submissions, it can be set to generate a Similarity Report. This means it will compare submitted work against a host of databases and highlight where similarities have been found in text.
Marking with Turnitin occurs online unless you are using an ipad, which enables offline marking. Each submission is private between the student, the marker(s) and staff with Tutor or Course Administrator access to the Moodle course.