15 facts about the magical world of Harry Potter you probably didn't know

July 31 is an important date for the Harry Potter universe and its fans. Wizards and muggles alike recognise the date as Harry's birthday, which coincides with creator JK Rowling's birthday. Harry was born on July 31, 1980, to Lily and James Potter. So on this special day, here are some lesser-known facts about the magical world...