In the Harry Potter series, the Hogwarts school of witchcraft and wizardry is divided into four houses, each bearing the last name of its founder - Godric Gryffindor, Salazar Slytherin, Rowena Ravenclaw and Helga Hufflepuff.

The Sorting

In the school's early days, students were handpicked by the founders. When they began to worry how students could be picked after their death, Godric Gryffindor took his hat off and the four "put some brains" in it. Now, at the beginning of each school year, the magical Sorting Hat is placed on each new student's head, at a ceremony named the Sorting ceremony, and the Sorting Hat announces the house that the student is bound to join. Before beginning the sorting, it sings a short ballad about the founding of the school and the four houses; the song is different every year and the Hat is said to take all the year writing the next one.

The hat sorts by judging the most obvious qualities of the student and choosing the most appropriate, although the student's own preferences do affect a difficult decision. The most clear example is Harry choosing Gryffindor over Slytherin in the first book.

House dynamics

The four houses are rather separate entities. Each has its own common room and dormitories, its own table at the great hall where meals are eaten and festivities held, and students mostly share lessons with other people of their same house. There's no rule against students from different houses mingling, but in practice a good majority of their social contacts tend to come from the same house. Each house has one teacher as its head; the remaining teachers are unaffiliated. Each house also has a house ghost, though exactly what function they serve (if any) is unknown.

A great deal of rivalry exists between the houses, not always friendly, especially when Slytherin is involved. This rivalry is demonstrated with the annual school competition for the House Cup which is determined by the amount 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 have the authority to grant and deduct points as they see fit in each instance. Some, like Severus Snape, the 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.

The four houses

Gryffindor

Gryffindor values courage and chivalry. Its emblematic animal is the lion and its colours are gold and dark red. Minerva McGonagall is the head of house, Nearly Headless Nick the house ghost.

As this is Harry Potter's house, its private quarters are the only ones that have been described in any detail and its members tend to get the most attention. The former are located in one of the castle's towers, where the entrance is guarded by a painting of a fat lady in pink. She permits entry only after being given the correct regularly changing password. Behind her is a large common room, with a fireplace, and two staircases leading up to the boys' and girls' dormitories. Harry shares his dormitory with Ron Weasley, Neville Longbottom, Seamus Finnigan and Dean Thomas. Hermione Granger shares her dormitory with Parvati Patil and Lavender Brown. Other notable Gryffindors include the rest of the Weasley family.

Slytherin

Slytherin values ambition, cunning and slyness. Its emblematic animal is the serpent and its colours are green and silver. The Slytherin head is Severus Snape, its ghost the Bloody Baron.

Contrary to the beliefs of his peers, Salazar Slytherin wanted a stricter policy of admittance - one limited to pureblood students. The controversy this created eventually led to Salazar leaving the school, leaving the Chamber of Secrets behind. A millenium later, the house's students are still considered affiliated with Salazar's views; sometimes undeservedly, sometimes not. Blood purity is certainly one of the things in Voldemort's agenda.

Among the house's more infamous students are Draco Malfoy,Tom Riddle,and Bellatrix Lestrange. See Minor Slytherins for others.

Ravenclaw

Ravenclaw values intelligence, knowledge and wit. Its emblematic animal is, oddly enough, the eagle and its colours are blue and bronze (silver in the films). The Ravenclaw head is Filius Flitwick, the house ghost the Grey Lady.

This house includes Penelope Clearwater (Percy Weasley's girlfriend), Cho Chang (Harry Potter's ex-girlfriend and seeker for the Ravenclaw Quidditch team), and Luna Lovegood. For more, see Minor Ravenclaws.

Hufflepuff

Hufflepuff values loyalty, patience, hard work and justice; it's also the most inclusive of the four houses. Its emblematic animal is badger and yellow and black are its colours. Professor Sprout is the head of Hufflepuff, and the Fat Friar its ghost. Less spectacular than the rest, Hufflepuff can be unfairly stereotyped as being unintelligent or meek.

Cedric Diggory was their Quidditch captain and seeker. For more members, see Minor Hufflepuffs.