A Postdoctoral Scholar (colloquially "post-doc") is a temporary research position held by a person who has completed his or her doctoral studies. Postdoctoral positions commonly last for periods ranging between six months and five years, and have traditionally been dedicated purely to research; so-called "teaching post-docs" are now being offered for those who seek to focus on teaching in their careers, however.

In the humanities, the appointee is typically given a title such as research associate, or sometimes research assistant professor. However in the sciences a post-doctoral researcher must work towards the position of research associate which is considered to rank above a post-doc position and commands a higher pay scale.

In the United Kingdom, one-quarter of those who attain doctorates in the natural sciences go on to postdoctoral work. This contributed to 85% of research-only staff in universities being on fixed term contracts in the UK. In North America, nearly all of those who attain doctorates in the natural sciences go on to postdoctoral work.

United States

Advantages to working as a post-doc
A post-doctoral period, under the most ideal circumstances, could possibly offer an opportunity to further one's research interests. Normally postdocs may travel freely to conferences and administer their own funds,[citation needed] and working hours are usually flexible.

Also, whereas faculty positions frequently use the 40%, 40%, 20% workload division between research, teaching, and service, respectively, post-docs can devote 100% of their work hours to research. Advising students, going to faculty meetings, preparing lectures, etc. are not compulsory. Importantly, the research and data collected during the post-doctoral period may benefit the individual in question for years beyond. Methods or subjects established during the postdoctoral period are usually the basis of one's future research. In addition, due to the highly specialized nature of dissertation research, postdoctoral training can provide an opportunity to acquire additional technical and research skills that were not acquired during the graduate education program.

Postdoctoral experience is required for some new faculty hiring in research oriented institutions. New faculty having postdoctoral training often begin at higher salaries than their peers who have not. This can not only affect starting salary but also each raise or promotion to come, as compensation is sometimes calculated in part based on starting salary.

A postdoc working at a company may have a better chance to become an permanent employee in the company. Some companies hire postdocs with an intent to hire them as permanent employees later.

A postdoctoral position may also offer an opportunity to change your career or research direction to an area that may be of more interest to you.

Disadvantages to working as a post-doc
About half of PhDs choose this route of career progression, often in order to obtain a faculty position; however, a very large percentage of post-docs never achieve this.

The common 'lore' is that before entering certain fields, a post-doc appointment may be a necessary step in order to gain greater knowledge and experience, make connections, and build a name for oneself in research circles.

Conditions of employment for post-doctoral fellows vary greatly. Some typical problems raised are:

- There may be no job duties or job descriptions given for a postdoctoral fellow.
- The employment of the fellow is salaried, well below industry salaries, and "at will."
- Postdoctoral appointments last from 1-5 years on average with a decreasing yield of between 17-20% of postdoctoral fellows obtaining a permanent faculty position.
- The fixed term nature of the employment means post-docs are particularly vulnerable to bullying and unreasonable demands.

To quote the President of the University of Southern California, “One of the reasons postdocs have become increasingly popular is because a postdoc is less expensive than a PhD student--you have to pay the PhD students' tuition plus a $15,000 stipend. And the postdoc spends 80 hours a week or more on research while the PhD has to go to class. That makes postdocs very, very attractive."

In traditional lore a postdoctoral fellowship may also be seen as a valuable tool to distinguish oneself from other candidates when entering the job market. Such appointments are often the "stepping stone" whereby a graduate student can improve their publication record and hence progress to a permanent position.

In many academic fields, post-doctoral appointments — traditionally optional — have become mandatory as tenure-track positions are simply unavailable for those who have not completed post-doctoral or adjunct positions. Without post-doctoral experience, most fresh doctorates lack the connections and prominence needed to secure a better academic job.

As the doctorate degree is, by definition, the highest awarded in a field, no degree is given at the completion of a post-doctoral position. Some post-doctoral positions share more in common with low-paid adjunct jobs than continuing education. In some fields (especially life sciences) in some countries, like the United States of America, there are so many graduates that post-doctoral work is almost necessary.

Often academics will take a succession of post-doctoral positions before achieving a faculty position or leaving academia.

 Australia

Although some institutions consider (early career) postdocs to still be under training (e.g. CSIRO), most consider a postdoctoral position simply as a short term job taken on after a PhD. Within universities post-doctoral positions are considered academic staff rather than student or general staff positions.

Postdoc salaries are generally higher than in other countries; e.g. the minimum Level A academic salaries for doctoral qualified employees beginning in 2008 are AU$66,155 p.a. at the University of Sydney, AU$63,451 p.a. at the University of Melbourne, and AU$67,140 p.a. at the University of New South Wales. Another method of funding post-doc salaries is through the highly competitive Australian Research Council (ARC) Discovery Projects. Through this program the salary for 3 year Australian Postdoctoral Fellowships beginning in 2009 is AU$61,399 p.a.

Furthermore, a relatively generous (mandatory) superannuation payment of 11-17% is paid by Universities.