Professor in 859: Fatima al-Fihri endows al-Qarawiyyin

How long does it take to become a professor? Typically ten to fifteen years after secondary school: a bachelor's degree of three to four years, a doctorate of four to seven, then two to six years of postdoctoral or fixed-term posts before a first permanent appointment. Tenure or an equivalent permanent status usually arrives in a candidate's mid-to-late thirties, and in German-speaking and some Asian systems often later still.

Tenure is an indefinite appointment that can be revoked only for serious cause, designed to protect scholars who publish unpopular findings. The American standard was set by the AAUP's 1940 Statement of Principles, typically after a six-year probation and an up-or-out review. Other systems protect professors differently: German professors are civil servants, while the UK abolished formal tenure in its 1988 Education Reform Act.

What is the difference between assistant, associate and full professor? In the North American system they are career ranks: assistant professors are on probation for tenure, associate professors have usually just earned it, and full professors have passed a second promotion review. In the UK and much of the Commonwealth, the ladder runs lecturer, senior lecturer, reader, professor — so "professor" there means only the top rank, not any university teacher.