The Common Rooms on Pottermore are places where users can see what is happening with the members of their own house.
Slytherin Common Room
The Slytherin Common Room has an aura of darkness, with eerie green light filtering in through the windows that look out into the Hogwarts lake. A fire burns underneath an ornate mantelpiece which is decorated with skulls and the emblem of Slytherin, a serpent. Comfortable couches and tables emphasize the dark stone wall interior. Impossible to enter without a password which changes every two weeks, the entry is hidden in the dungeons. Slytherin and Gryffindor have been said to be the opposite polarities of eachother, and this is definitely reflected in their Common Rooms.
Gryffindor Common Room
worse looking one :)
Hufflepuff Common Room
- Main article: Hufflepuff Common Room
The Hufflepuff common room is entered from the same corridor as the Hogwarts kitchens. Proceeding past the large still life that forms the entrance to the latter, a pile of large barrels is to be found stacked in a shadowy stone recess on the right-hand side of the corridor. A sloping, earthy passage inside the barrel travels upwards a little way until a cosy, round, low-ceilinged room is revealed, reminiscent of a badger's set. It is sunny and warm, with windows level with the ground and filled with exotic plants that Professor Sprout brings.
Ravenclaw Common Room
The Ravenclaw Common Room is a bookworm's paradise. There is a large room that serves as a library, and it is said that there are almost as many books there as in the main library, even if the room looks much, much smaller. A statue of Rowena Ravenclaw stands at the entrance to the library. Light floods in from windows close to the ceiling. This is the only common room without a fireplace in the main part of the common room. It is in one of the tallest towers in Hogwarts. To enter it, you must answer a riddle; there is no password.The tower gives the best view, and the ceiling depicts the night sky .