An  essay mill (or paper mill) is a ghostwriting service that sells essays and other homework writing to university and college students. Since plagiarism is a form of academic dishonesty or academic fraud, universities and colleges may investigate papers suspected to be from an essay mill by using Internet plagiarism detection software, which compares essays against a database of known essay mill essays and by orally testing students on the contents of their papers. However, many essay mills guarantee that a unique essay will be composed by a ghost author and pre-screened with plagiarism detection software before delivery, and as such will be undetectable as an essay mill product. custom written essays