Students' union in the context of "Tudor bonnet"

A collegiate university is a university where functions are divided between a central administration and a number of constituent colleges. Historically, the first collegiate university was the University of Paris and its first college was the Collège des Dix-Huit. The two principal forms are residential college universities, where the central university is responsible for teaching and colleges may deliver some teaching but are primarily residential communities, and federal universities where the central university has an administrative (and sometimes examining) role and the colleges may be residential but are primarily teaching institutions. The larger colleges or campuses of federal universities, such as University College London and University of California, Berkeley, are effectively universities in their own right and often have their own student unions.

For universities with residential colleges, the principal difference between these and non-collegiate halls of residence (or dormitories) is that "colleges are societies (Latin collegia), not buildings". This is expressed in different ways in different universities; commonly students are members of a college, not residents of a college, and remain members whether they are living in the college or not, but this is not universal and the distinction may be drawn in other ways (see, e.g., the University of Otago below). Residential colleges also commonly have members drawn from the university's academic staff in order to form a whole academic community. Students in residential colleges are often organised into a junior common room, with postgraduate students in a middle common room, and academic staff forming a senior common room.

A student center (or student centre) is a type of building found on university and some high school campuses. In the United States, such a building may also be called a student union, student commons, or union. The term "student union" refers most often in the United States to a building, while in other nations a "students' union" is the student government. Nevertheless, the Association of College Unions International (largely US-based) has several hundred campus organizational members in the US; there is no sharp dichotomy in interpretation of union in this context. The US usage in reference to a location is simply a shortened form of student union building.

The National Union of Students (NUS) is a confederation of student unions across the United Kingdom. Approximately 600 student unions are affiliated, accounting for more than 95% of all higher and further education unions in the UK. Although the National Union of Students is the central organization for all affiliated unions in the UK, there are also the devolved national sub-bodies: NUS Scotland in Scotland, NUS Wales (UCM Cymru) in Wales and NUS-USI in Northern Ireland (the latter being jointly administered by Aontas na Mac Léinn in Éirinn).

NUS is a member of the European Students' Union.

A common room is a group into which students (and sometimes the academic body) are organised in some universities, particularly in the United Kingdom, normally in a subdivision of the university such as a college or hall of residence, in addition to an institution-wide students' union. They represent their members within the hall or college, operate certain services within these institutions such as laundry or recreation, and provide opportunities for socialising. There are variations based on institutional tradition and needs, but classically the following common rooms will exist:

• A junior common room (JCR) – for undergraduate students
• A middle common room (MCR) – for post-graduate students (in colleges with a large number of post-graduate students)
• A senior common room (SCR) – for academic members of the college

Common rooms are particularly found at collegiate universities such as Oxford, Cambridge, Durham, York and Lancaster, but can also be found (often only the JCR) at non-collegiate universities, where they are normally associated with halls of residence. A significant difference between colleges and halls of residence generally is that students continue to be members of a college when not resident in the college; thus college JCRs serve all students who are members of the college, whether or not they live in college accommodation, while hall JCRs serve only residents of that hall.