The completion of a PhD is typically required for employment as a university professor, researcher, or scientist in many fields.

• A PhD candidate must submit a project, thesis, or dissertation often consisting of a body of original academic research, which is in principle worthy of publication in a peer-reviewed journal.
• The specific requirements to earn a PhD degree vary considerably according to the country, institution, and time period, from entry-level research degrees to higher doctorates.
• During the studies that lead to the degree, the student is called a doctoral student or PhD student; a student who has completed any necessary coursework and related examinations and is working on their thesis/dissertation is sometimes known as a doctoral candidate or PhD candidate.
• A student attaining this level may be granted a Candidate of Philosophy degree at some institutions or may be granted a master's degree en route to the doctoral degree.