The University of Oxford comprises 39 Colleges and 7 religious Permanent Private Halls (PPHs), which are autonomous self-governing corporations within the university. All teaching staff and students studying for a degree of the university must belong to one of the colleges or PPHs. These colleges are not only houses of residence, but have substantial responsibility for the teaching of undergraduates. Generally tutorials (the main method of teaching in Oxford) and classes are the responsibility of colleges, while lectures, examinations, laboratories and the central library are run by the university.

Undergraduate and graduate students may name preferred colleges in their applications. For undergraduate students, an increasing number of departments practice reallocation to ensure that the ratio between potential students and subject places available at all colleges are as uniform as possible. For the Department of Physics, reallocation is done on a random basis after a shortlist of candidates is drawn up and before candidates are invited for interviews at the university blank">http://www.physics.ox.ac.uk/admissions/FAQs08.pdf.

For graduate students, many colleges express a preference for candidates who will be undertaking research in an area of interest of one of its fellows. St Hugh's College, for example, states that it accepts graduate students in most subjects, principally those in the fields of interest of the Fellows of the college http://www.admin.ox.ac.uk/postgraduate/colleges/shug.shtml.

A typical college consists of a _hall for dining, a chapel, a library, a college bar, senior, middle (postgraduate) and junior common rooms, rooms for 200-400 undergraduates as well as lodgings for the head of the college and other dons. College buildings range from the medieval to very modern buildings, but most are made up of interlinked quadrangles (courtyards), with one or more large wooden gates controlling entry from the outside.