As I mentioned in my previous article, each fandom has a canon. It depends on the fandom itself what is considered canon. In sports, their canon might be the rules and regulations that the sport runs by. In a fandom such as Star Wars some fans may consider only the films canon, others might include the extensive extended universe tie in novels. Game of Thrones fans might consider their canon either the show or the books, or attempt to meld the two.
There are other choices other then strict canon, such as fanon, semi-canon, Alternate Universe, and of course non-canon.