This document discusses the history of fanfiction and provides examples of different types of fanfics, including canon, alternate universe, and mirror universe stories. It notes that while some fanfics start out innocently, others can be of poor quality. As an example, it specifically calls out "My Immortal" as literally the worst fanfic ever written. The document also lists several popular fictional series that fanfics are often based on, such as Star Trek, Harry Potter, and The Mortal Instruments.