In the U.S., "professors" commonly occupy any of several positions in academia, typically the ranks of assistant professor, associate professor, or professor. The same terms are used outside the U.S., although they often denote different roles from in the U.S. system. However, the majority of university lecturers and instructors in the United States today (2015) do not occupy these tenure-track ranks, but are part-time adjuncts.
Research and education are among the main tasks of non-adjunct professors, with the amount of time spent on research or teaching depending strongly on the type of institution. Publication of articles in conferences, journals, and books is essential to occupational advancement. As of August 2007 teaching in tertiary educational institutions is one of the fastest growing occupations, topping the U.S. Department of Labor's list of "above average wages and high projected growth occupations," with a projected increase of 524,000 positions between 2004 and 2014. In 2011, a survey conducted by TIAA-CREF Institute senior researcher Paul J. Yakoboski estimated that 73% of professors with senior tenure ranged between the ages of 60 and 66 and that the remaining 27% were above the age of 66. Yakoboski estimated that 75% of these professors have acknowledged that they have made no preparations for retirement due to the ongoing financial crisis and reluctance to leave their profession. A 2013 survey conducted by Fidelity Investments would echo similar results when the question about retirement came up.
The term "professors" in the United States refers to a group of educators at the college and university level. In the United States, while "Professor" as a proper noun (with a capital "P") generally implies a position title officially bestowed by a university or college to faculty members with a PhD or the highest level terminal degree in a non-academic field (e.g. MFA), the common noun "professor" is often used casually to refer to anyone teaching at the college level, regardless of rank or degree. At some junior colleges without a formal ranking system, instructors are accorded the courtesy title of "professor."