with its own internal structure and activities. Not all colleges offer all courses, but they generally cover a broad range of subjects. The colleges are: The permanent private halls were founded by different Christian denominations. One difference between a college and a PPH is that whereas colleges are governed by the fellows of the college, the governance of a PPH resides, at least in part, with the corresponding Christian denomination. The five current PPHs are: The PPHs and colleges join as the Conference of Colleges, which represents the common concerns of the several colleges of the university, to discuss matters of shared interest and to act collectively when necessary, such as in dealings with the central university. The Conference of Colleges was established as a recommendation of the Franks Commission in 1965. Teaching members of the colleges (i.e. fellows and tutors) are collectively and familiarly known as dons, although the term is rarely used by the university itself. In addition to residential and dining facilities, the colleges provide social, cultural, and recreational activities for their members. Colleges have responsibility for admitting undergraduates and organising their tuition; for graduates, this responsibility falls upon the departments. There is no common title for the heads of colleges: the titles used include Warden, Provost, Principal, President, Rector, Master and Dean. Finances In 2017–18, the university had an income of £2,237m; key sources were research grants (£579.1m) and academic fees (£332.5m). The colleges had a total income of £492.9m. While the university has a larger annual income and operating budget, the colleges have a larger aggregate endowment: over £4.9bn compared to the university's £1.2bn. The central University's endowment, along with some of the colleges', is managed by the university's wholly-owned endowment management office, Oxford University Endowment Management, formed in 2007. The university used to maintain substantial investments in fossil fuel companies. However, in April 2020, the university committed to divest from direct investments in fossil fuel companies and to require indirect investments in fossil fuel companies be subjected to the Oxford Martin Principles. The total assets of the colleges of £6.3 billion also exceed total university assets of £4.1 billion. The college figure does not reflect all the assets held by the colleges as their accounts do not include the cost or value of many of their main sites or heritage assets such as works of art or libraries. The university was one of the