He wants to know more about the many jobs listed in small print in the credits at the end of movies. Some of these jobs have funny names -- like boom operator. It sounds like someone who works with explosives. But in this case a boom is a long pole with a microphone at the end.

Boom operators are part of the sound production team for movies and TV shows. They have to keep the microphone over the heads of the actors. They have to keep it low enough to hear them but high enough to stay out of the picture. Otherwise the director might get angry.

If moviemakers yell "get a grip," they are not telling people on the set to get hold of reality. A grip is a lighting and camera support person. Grips set up the lighting for each shot and handle the equipment to help the camera operator get the best shot.

A key grip supervises other grips. And grips work with gaffers. A gaffer is a chief lighting technician who supervises electricians.

A greensman provides any plants, real or fake, that are needed on the set. The job is done under the supervision of the set decorator or production designer. Wranglers are responsible for animals used in a production. This might sound like fun, unless you have to work on a movie like, say, “Snakes on a Plane.”

A script supervisor keeps detailed records of shots and is responsible for continuity. Everything has to be where it is supposed to be, not only within a scene but from one scene to the next. If not, the audience might notice a blooper, a mistake. Even a small problem with continuity might mean that a scene has to be reshot.

Sometimes actors may not want to appear in scenes themselves. Or there may be a technical reason not to. So the director will use a body double. The hope is that no one in the audience will see a difference. Professional ballerina Sarah Lane was a body double in the Oscar-winning movie “Black Swan.” She performed much of the dancing for the star, Natalie Portman.

Stars, of course, usually get credit at the beginning of a movie, along with producers and directors. But it takes all those other people listed at the end to make it all possible. Think about that the next time you leave a theater while the credits are still rolling on the screen.