Amie Saw the Movie the Phantom of the Opera and Really

Amie saw the movie The Phantom of the Opera and really liked it. She was familiar with the music because her mother purchased the CD after she saw the play in New Orleans, but Amie had never seen it before. Once she saw the movie, however, she got really interested in it and even read the book. She also has searched the Internet and found one site that other fans use to contact one another and exchange their opinions and experiences. She even rented the silent version of the movie, but the ending was defective. She asked other fans, through the Internet, about the ending and received feedback immediately. From this site she can also link to several fans' personal online "diaries" about Phantom. She has also found an area on Fanfiction.com where people post their own stories about Phantom, and she uploaded one herself and received favorable reviews. What are the sites where Amie can interact with other fans and those that are other fans' electronic diaries called, and why should advertisers be aware of them?