Academic rank (also scientific rank) is the hierarchical rank of a teacher, researcher or other employee in a college, high school, university or research establishment. The academic ranks indicate relative importance and power of individuals in academia.
The academic ranks are specific for each country, there is no worldwide-unified ranking system. Among the common ranks are professor, associate professor (docent), assistant professor and lecturer/instructor.
Professor (commonly abbreviated as Prof.) is an academic rank at universities and other post-secondary education and research institutions in most countries. Literally, professor derives from Latin as a 'person who professes'. Professors are usually experts in their field and teachers of the highest rank.
In most systems of academic ranks, "professor" as an unqualified title refers only to the most senior academic position, sometimes informally known as "full professor". In some countries and institutions, the word professor is also used in titles of lower ranks such as associate professor and assistant professor; this is particularly the case in the United States, where the unqualified word is also used colloquially to refer to associate and assistant professors as well, and often to instructors or lecturers.
Lecturer is an academic rank within many universities, though the meaning of the term varies somewhat from country to country. It generally denotes an academic expert who is hired to teach on a full- or part-time basis. They may also conduct research.
A research fellow is an academic research position at a university or a similar research institution, usually for academic staff or faculty members. A research fellow may act either as an independent investigator or under the supervision of a principal investigator.
Research fellow positions vary in different countries and academic institutions.
Distinguished professor is an academic title given to some top tenured professors in American universities, schools, or departments. Some distinguished professors may have endowed chairs.
Often specific to one institution, titles such as "president's professor", "university professor", "distinguished professor", "distinguished research professor", "distinguished teaching professor", "distinguished university professor", or "regents professor" are granted to a small percentage of the top tenured faculty who are regarded as particularly important in their respective fields of research. Some institutions grant more university-specific, formal titles such as M.I.T.'s "Institute Professor", Yale University's "Sterling Professor", or Duke University's "James B. Duke Professor".