 One of the challenges facing universities is that in some cases, students may submit essays purchased from an essay mill (or "paper mill") as their own work.An "essay mill" is a ghostwriting service that sells pre-written essays to university and college students.Since plagiarism is a form of academic dishonesty or academic fraud, universities and colleges may investigate papers they suspect are from an essay mill by using plagiarism detection software, which compares essays against a database of known mill essays and by orally testing students on the contents of their papers.