The producer is in charge of running the financial and technical end of things, and often works closely with the director toward a shared vision of the film. The producer often has a hand in casting or assigning jobs.
The DP is in charge of cinematography. The DP will work with the lighting crew (the electricians and the grips) to ensure the proper mood for each scene.
Key Grip, Best Boy Grip or just plain Grip are all terms used to refer to the lighting and rigging technicians on the film.
In addition to overseeing the set, craft services also provides a buffet of food for cast and crew.
A production assistant is a jack of all trades, responsible for tasks ranging from coffee runs to carrying equipment to catering to the whims of the stars.
Any CGI used in a film is done during post-production by a digital effects artist.
A stunt double takes the place of an actor during dangerous filming. A body double is used to replace the body of another actor. Most often, body doubles are used when the actor involved is taking part in a dangerous stunt or is supposed to be nude. One famous body double was used to film the audition scene in "Flashdance."