A technical advisor is an individual who is expert in a particular field of knowledge, hired to provide information in that field to a movie or television director, to ensure that this area of knowledge is portrayed accurately in the production. For example, a director for a show involving combat aviation might hire one or more current or former combat pilots to serve as technical advisors. Similarly, a period movie may include one or more historians of the period, or eyewitnesses if possible, for the same purpose.
These individuals typically answer to the director. Their expertise adds realism both to the acting and to the setting of a movie. Some advisors for military movies have been known to run miniature boot camps to give actors a first-hand experience of a military setting.