A business consultant (from Latin consultare, "to discuss") is a professional who provides professional or expert advice in a particular area such as security (electronic or physical), management, accountancy, law, human resources, marketing (and public relations), finance, engineering, science, digital transformation or any of many other specialized fields. The overall impact of a consultant is that clients have access to deeper levels of expertise than would be feasible for them to retain in-house, and may purchase only as much service from the outside consultant as desired.