During their first four years, students need only to pass each of their subjects before advancing to the next level the following year. Regular exams and lessons usually seem to be graded on a numerical scale from with 100 being full marks. If a student fails their year, they need to repeat it in the following school year.

To qualify as a registered practitioner of magic, students must study for the compulsory Ordinary Wizarding Level (O.W.L.) examinations taken in the fifth year. If passed, a student may proceed to the Nastily Exhausting Wizarding Test (N.E.W.T.) level, a more advanced exam covering fewer subjects in more depth, taken at the end of the seventh year.

Subjects are graded on the following scale:

Passing Grades

O = Outstanding
E = Exceeds Expectations
A = Acceptable
Failing Grades

P = Poor
D = Dreadful
T = Troll

The O.W.L.s roughly corresponds to the O(rdinary)-level (now replaced by GCSE), and the N.E.W.T.s to the A-level examinations used in the English secondary school system. In order to proceed to a N.E.W.T., a student usually needs to have achieved at least an E in the O.W.L. of the same subject, although some professors (e.g. Professor Snape) insist upon a grade of O. Students who fail their exams or who do not achieve high enough grades continue to take O.W.L. classes in their sixth and seventh years.[HP6]

At the end of their fifth year, students speak briefly with their head of house to decide which classes to continue on in depending on their O.W.L. scores and their goals after school. The classes they decide to continue are considerably more advanced.

Due to the fact that they dropped one or more classes, students in their sixth and seventh year may get several class sessions off per week. The heavy workload that each of these classes require means that students usually spend these times studying and doing homework. At the end of their seventh and final year, students take the N.E.W.T. exams, which test what the student has learned over the past two years. Many professions require high grades in these tests, meaning that students must work very hard to ensure that they pass.

In their sixth year, students who will be seventeen by 31 August may take a twelve week course of Apparation for twelve Galleons. The instructor is Wilkie Twycross. Those who will not turn seventeen in time will presumably take the classes in seventh year.

Hogwarts was founded over a thousand years ago (exact date unknown) by two wizards and two witches: Godric Gryffindor, Salazar Slytherin, Rowena Ravenclaw, and Helga Hufflepuff. These four were among the most celebrated European wizards and witches of the time, and they personally trained all their students. All four founders selected their students according to strict criteria. Slytherin, however, desired to limit school admissions only to students born to magical parents, also known today as Purebloods; this desire brought him into conflict with the other founders, Gryffindor in particular. Tension arose between the other Founders as well and the once-great friendship of Ravenclaw and Hufflepuff failed as disastrously as that of Gryffindor and Slytherin. Divided, the four founders and their houses each sought to control the whole school, causing chaos. Slytherin eventually fled or was driven from the school and, though diminished by their loss, the remaining three founders re-established peace.

At some point before Slytherin departed, he had constructed the Chamber of Secrets and concealed a basilisk within it . According to legend, he left this for his progeny, so that, when an eventual successor ("the Heir of Slytherin") returned to the school he or she would be able to open the Chamber and unleash the monstrous basilisk within to purge the school of all Muggle-born students. The only descendant known to have discovered the Chamber is Tom Marvolo Riddle, later known as Lord Voldemort, the most feared Dark Wizard of all time.

About three hundred years after the school was founded, the Triwizard Tournament began between the three most prestigious magical schools in Europe: Hogwarts, Beauxbatons, and Durmstrang. This Tournament was considered the best way for wizards of different nationalities to meet and socialise. The Tournament was continued every five years until the too-high death toll caused it to be discontinued. After several attempts to reinstate the Tournament, in the year 1994 the Ministry of Magic decided to give it another try, after promising a big decrease in deaths. Only students age 17 and older may participate in the Triwizard Tournament.