Hogwarts is divided into four houses, each bearing the last name of its founder: Godric Gryffindor, Salazar Slytherin, Rowena Ravenclaw and Helga Hufflepuff. The houses compete throughout the school year, by earning and losing points for various events, for 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. Houses at Hogwarts are the living and learning communities for their students. Each house is under the authority of one of the Hogwarts staff members. The Heads of the houses, as they are called, are in charge of giving their students important information, dealing with matters of severe punishment, and responding to emergencies in their houses, among other things. Each year, year level groups of every separate house share the same dormitory and classes. The dormitory and common room of a House are, barring rare exceptions, inaccessible to students belonging to other Houses.
In the early day of Hogwarts, 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 they each added knowledge to it, allowing the Sorting Hat to choose the students 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 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.
The translators of the books’ foreign editions had difficulty translating the "house" concept; in countries where this boarding system does not exist, no word could adequately convey the importance of belonging to a certain house, the loyalty owed to it, and the pride taken in prizes won by the house.
Hogwarts' school year is structured in a similar way to other 'non-magical' schools and colleges in the UK, with a three-term year punctuated by holidays at Christmas and Easter and bounded by the long summer holiday of nine weeks. Term begins every year on 1 September, and finishes at the end of June the following year. Students have the option of staying at Hogwarts for the winter and spring holidays. Those who choose to stay at the castle do not have lessons and attend a feast on Christmas Day. Students also do not have classes the week of Easter, but this is much less enjoyable due to the large amount of work that the teachers assign students at this time in preparation for final exams.
Other than the aforementioned breaks, and weekends, students do not receive any other holidays. There are normally four feasts per year, the start-of-term feast at the beginning of the school year and end-of-term feast at the end of the school year, as well as feasts at Halloween and Christmas. Feasts are also called to mark any special occasions, as in Goblet of Fire, when there was a feast to celebrate the beginning of the Triwizard Tournament.
Now that you know a little about the school and if you joined you obviously know about Harry you should be doing good.