A consultant is a professional who provides advice in a particular area of expertise such as accountancy, human resources, marketing, medicine, finance, the environment, technology, law, economics, public affairs, communication, engineering, sound system design, graphic design, or waste management.

A consultant is usually an expert or a professional in a specific field and has a wide knowledge of the subject matter. Thus, clients have access to deeper levels of expertise than would be feasible for them to retain in-house, and to purchase only as much service from the outside consultant as desired. A consultant usually works for a consultancy firm or is self-employed, and engages with multiple and changing clients. It is generally accepted good corporate governance to hire consultants.

How consultants work

 In other situations, companies implementing a major project may need additional experienced staff to assist with increased work during that period.Often a consultant provides expertise to clients who require a particular type of knowledge or service for a specific period of time, thus providing an economy to the client.