"Consultancy" redirects here. For companies, see Consulting firm.
A consultant (from Latin: consultare "to deliberate")[1] is a professional (also known as expert, specialist, see variations of meaning below) who provides advice or services in an area of specialization (generally to medium or large-size corporations).[2][3][4][5][6][7][8] Consulting services generally fall under the domain of professional services, as contingent work.[9]
The Harvard Business School defines a consultant as someone who advises on "how to modify, proceed in, or streamline a given process within a specialized field".[10]