Hogwarts Houses

The Hogwarts School of Witchcraft and Wizardry is divided into four houses, each bearing the last name of its founder: Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw and Salazar Slytherin.

House system
Houses at Hogwarts are the living and learning communities for its students. Each year group of a certain house shares the same Dormitory and classes. The houses compete throughout the school year, by earning and losing points for various events, The house with the most points wins the House Cup. Each house also has its own Quidditch team that competes for the Quidditch Cup. These two competitions breed rivalries between the houses, the greatest of which is that between Gryffindor and Slytherin.

Sorting
In the Hogwarts' early days, the four founders handpicked students for their Houses. When the founders worried how students would be selected after their deaths, Godric Gryffindor took his hat off and each "put some brains" in it, allowing the Sorting Hat to choose students. Now, at the beginning of each school year, the magical Sorting Hat is placed on each new student's head, during the Sorting ceremony. The Sorting Hat announces the house the student is bound to join. Before beginning the Sorting ceremony, it sings a short song about the founding of the school and the four houses; the Sorting Hat's songs are different every year, and the Hat is said to take all year composing the next one (according to Ron Weasley, at least). The songs tends to give advice in troubled times.

The Hat sorts by judging each student's qualities and placing them in the most appropriate house. The student's own choices may affect the decision: the clearest example is the Hat telling Harry Potter that he would do well in Slytherin in the first book, but ultimately selecting Gryffindor after Harry asks it not to put him in Slytherin. Another example is in the fifth book when Hermione Granger states that The Sorting Hat considered sorting her into Ravenclaw, but after she clearly stated in a previous chapter that she wanted to be in Gryffindor, her choice probably ultimately overrides The Sorting Hat, resulting in her placement into Gryffindor. Albus Dumbledore later explains to Harry that this is how it should be, when one considers how a person's choices define them more than their abilities. It is in fact likely that the Hat selects houses according to the predetermined decisions of an informed student, and only genuinely selects those who have no preconceptions or expectations (according to Horace Slughorn, house affiliations tend to run in families, and it is notable that Ron Weasley could not consider being in any house other than that which every other member of his family had been in; however, when Harry mentions this, Hermione points out that Parvati and Padma Patil, who are twins, are sorted differently (into Gryffindor and Ravenclaw, respectively), suggesting that the twins may have wanted to be in their respective houses prior to sorting). For example, every member of the Black family had been sorted into Slytherin, with Sirius Black being the sole exception, which was remarked upon by Slughorn, its Head. On the other hand, many House members appear to share common traits: it is unknown if these are present before Sorting and used as criteria, or if they are inculcated into students through their presence in the House.

The hat does not just consider the student's most obvious strengths; it also sees a student's potential qualities. "You could be great you know, it's all here in your head, and Slytherin will help you on the way to greatness", it says to Harry when it suggests Slytherin as the best house for his future. Similarly, Hermione and Neville Longbottom do not immediately jump out as prime examples of Gryffindor courage in the beginning of the series, but they have both gained a tremendous amount of courage as they have grown. Hermione is even asked point-blank, why the Hat didn't put her in Ravenclaw, considering her intelligence. Her answer is that the Hat "considered it, but decided on Gryffindor in the end" (notably, she wanted to be in Gryffindor before even arriving at the school).

However, just because a student is sorted into one particular house doesn't necessarily mean that that student will always be truly suited to that house, or that the student can't display qualities of other houses. The Sorting Hat will only sort the student based on qualities it sees at that particular age. Dumbledore himself has said that he thinks "we sort too soon". Peter Pettigrew, for example, was sorted into Gryffindor but ultimately proved himself to be a cowardly man. Similarly, Severus Snape was a Slytherin but throughout his life, displayed as much courage and bravery as any Gryffindor.

House dynamics
The four houses are rather separate entities. Each has its own Common Room and Dormitory, its own table in the Great Hall, and students mostly share lessons with classmates of their same house. There is no rule against students from different houses mingling, but in practise, a good majority of social interactions occur within the same house. Each house has one teacher who acts as its Head of House. Each house also has a House Ghost. The function they serve (if any) is unknown, although they might be like house Mascots. Each Head of House and house ghost was previously a pupil within that house.

A great deal of rivalry exists between the houses, not always friendly. This rivalry is demonstrated in the Quidditch matches and the annual school competition for the House Cup, which is determined by the number of points earned or lost by each member of the rival houses. These points are awarded or taken based on students' conduct throughout the school year. All members of the faculty and the Head Boy and Girl have the authority to grant and deduct points as they see fit in each instance. Prefects also have this authority, though they cannot take points from another prefect. Some, like Severus Snape, the former Potions master, tend to favour their own house, but that does not seem to be against the rules. He is despised by many students, other than those in Slytherin, where he is very popular. It is not known how much favouritism the Hufflepuff and Ravenclaw Heads show, although it can be deduced that it's minimal or non-existent, as both Professor Filius Flitwick (of Ravenclaw) and Professor Pomona Sprout (Hufflepuff) are kind, lighthearted people, who obviously want to win the House and Quidditch Cups but are not as vindictive as Snape in going about it. It is known that Professor Minerva McGonagall, the stern head of Gryffindor, does not show much favouritism towards her house. In fact, she deducted 50 points apiece and awarded detentions to three students in her house (Harry Potter, Hermione Granger, and Neville Longbottom when they were caught out of bed after hours in Harry's first year), and supported Professor Snape wholeheartedly in giving Harry detentions for the rest of the school year, even on overlapping Quidditch matches, after Harry used the Sectumsempra spell on Draco Malfoy in Harry's sixth year.

According to Rubeus Hagrid, "every wizard that's ever gone bad was in Slytherin," (though this is for the most part correct, there are a few exceptions, former Gryffindor Peter Pettigrew the most notable of them; Hagrid's statement here is also interesting, as at that time he surely would have thought Sirius Black, an ex - Gryffindor student, to have been a Dark wizard). None of this necessarily means, however, that all Slytherins are evil. Andromeda Tonks and Horace Slughorn are examples of this. Slytherins are chosen for their cunning and Pure-blood heritage (although Blood purity does not appear to be essential - Lord Voldemort and Snape were Half-bloods, though they both are prejudiced. It has also been said that all four houses must band together and fight as one if Hogwarts is to stand. It must be remembered that all of the Houses have their virtues and flaws: none are inherently good or evil. Slytherins may have earned their reputation as evil because they show such contempt towards Gryffindor, the protagonist house. They also do not show much generosity towards other houses either, whether those in them are pure-blood or not.

House rivalry is most seen between Slytherin and Gryffindor ("Gryffindor and Slytherin students loathed each other on principle"). This rivalry likely goes back to the days of Godric Gryffindor and Salazar Slytherin after they founded Hogwarts, because the Sorting Hat said that they were the best of friends before they founded the school. While it is not clear if there is a similar rivalry between Ravenclaw and Hufflepuff, it seems very much unlikely due to the cheerful disposition of the Heads for said Houses, as opposed to the contempt of Professor Snape and the passion of Professor McGonagall (Rowena Ravenclaw and Helga Hufflepuff, however, once great friends, are documented as having had a severe falling out at some point by the Sorting Hat's song in 1996. However, Ravenclaw and Hufflepuff house members seem to get along just fine, as shown with Cho Chang and Cedric Digggory, who were dating. Also, if the two were rivals it would be more obvious, however the two houses seem to be friendly.

Usually, though not always, the other two houses appear (in Harry's eyes) to support Gryffindor in its rivalry with Slytherin, which again is reminiscent of how Slytherin was in the end opposed by all three of the other Founders. One exception to this occurred when Ravenclaw, Hufflepuff, and Slytherin all initially supported Hufflepuff's Cedric Diggory instead of Gryffindor's Harry Potter in the Triwizard Tournament. Also in the first Quidditch match of 1996, it is said that many of the Hufflepuffs and Ravenclaws had "taken sides" in the Gryffindor vs Slytherin match, but does not specify which Houses took which side.

Gryffindor
Gryffindor values bravery, daring, nerve, and chivalry. Its emblematic animal is the lion and its colours are scarlet and gold. Minerva McGonagall is the most recent Head of Gryffindor. Sir Nicholas de Mimsy-Porpington aka Nearly Headless Nick is the house ghost. The founder of the house is Godric Gryffindor. Gryffindor corresponds to the element of Fire. The common room is located in one of the highest towers at Hogwarts, the entrance is situated on the seventh floor in the east wing of the castle and is guarded by a portrait of The Fat Lady. She permits entrance if given the correct password which is changed numerous times throughout the school year.

Hufflepuff
Hufflepuff, founded by Helga Hufflepuff, is the most inclusive among the four houses, valuing hard work, patience, loyalty, and fair play rather than a particular aptitude in its members. Its emblematic animal is the badger, and yellow and black are its colours. Pomona Sprout is the Head of Hufflepuff. The Fat Friar is its ghost. Hufflepuff corresponds roughly to the element of earth. The Hufflepuff Dormitories and common room are located somewhere in the basement, near the castle's kitchens.

Ravenclaw
Ravenclaw values intelligence, knowledge and wit. Its emblematic animal is the Eagle, and its colours are blue and bronze. The Ravenclaw Head is Filius Flitwick. The ghost of Ravenclaw is revealed in Book 7 to be the Grey Lady, who is the daughter of Rowena Ravenclaw called Helena Ravenclaw. The house was founded by Rowena Ravenclaw. Ravenclaw corresponds roughly to the element of air. The Ravenclaw common room and dormitories are located in a Tower on the west side of the school. Ravenclaw students must answer a question as opposed to giving a password to enter the dormitories like it is for Gryffindors, Hufflepuffs, and Slytherins.

Slytherin
Slytherin house values ambition, cunning and resourcefulness and was founded by Salazar Slytherin. Its emblematic animal is the serpent, and its colours are green and silver. Professor Horace Slughorn was the Head of Slytherin during the 1997–1998 school year, replacing Severus Snape, who as well, replaced Slughorn when he retired for the first time several years ago. The Bloody Baron is the house ghost. Slytherin corresponds roughly to the element of water. The Slytherin Dormitories and common room are reached through a bare stone wall in the Dungeons. The Slytherin common room is a long, low underground room (probably under the Hogwarts lake, thus Slytherin house's affiliation with water) with rough stone walls and round greenish lamps hanging from the ceiling.