Hogwarts is a text-based roleplaying game set in the world of Harry Potter.
This is not like Pottermore or any other Harry Potter fan site. This is cooperative storytelling where each person or "player" creates a student and writes for that character in stories with other characters. Each story is part of a school year. Each player is expected to be 15 years or older, although the character can be between 11 and 17.
If you're looking for a game, or another Pottermore site, this isn't it. If you like text-based RPGs, or "simming," have a look around.