A consultant is a professional who provides expert advice in a particular area such as security, management, education, accountancy, law, human resources, marketing (and public relations), finance, engineering, science or any of many other specialized fields.
A consultant is usually an expert or an experienced professional in a specific field and has a wide knowledge of the subject matter. The role of consultant outside the medical sphere (where the term is used specifically for a grade of doctor) can fall under one of two general categories
By hiring a consultant, clients have access to deeper levels of expertise that would be financially feasible for them to retain in-house on a long-term basis. Moreover, clients can control their expenditures on consulting services by only purchasing as many services from the outside consultant as desired.