Harry Potter (Fandom)

Harry Potter is one of the largest book fandoms. The Harry Potter series of seven fantasy novels written by the British author J. K. Rowling. The books chronicle the adventures of a wizard, Harry Potter, and his friends Ronald Weasley and Hermione Granger, all of whom are students at Hogwarts School of Witchcraft and Wizardry. The main story arc concerns Harry's quest to overcome the Dark wizard Lord Voldemort, whose aims are to become immortal, conquer the wizarding world, subjugate non-magical people, and destroy all those who stand in his way, especially Harry Potter.

Fandom
The Harry Potter fandom presence online is massive. On FanFiction.Net it still (as of 2013) has more posted works than any other fandom. Het, slash and gen are all popular, although femslash is less common. J.K. Rowling is supportive of fan activities; she has given her blessing for fanfiction and gives awards for her favorite fansites.

Fandom has embraced myriad forms of fan activities, such as fanfiction, fanart, fanvids, conventions, podcasts, cosplay, knitting, wizard rock, quidditch, wikis, discussion forums, etc. While the canon was still open, speculating about future plot developments was also widely popular. Hot topics included which ships were going to happen in canon (Harry/Hermione vs. Ron/Hermione) and whether Severus Snape was loyal to Lord Voldemort, Albus Dumbledore, or just himself. During the long wait for the next novel, some theories became quite fanciful.

Indeed, the fandom is so large and diversified that fans in one corner may have no idea what is happening in another corner. This balkanization is often deliberate.

Trivia

 * Harry Potter has more posted works on FanFiction.Net it (as of 2013).