If you've ever sat through a movie's closing credits, you know that film crews have their own funny language. Credits are filled with mysterious job titles like "best boy," "key grip" and "gaffer."

Visit a movie set, and you'll be even more confused. It seems like movie people have an odd name for every worker, piece of equipment and shot involved in film production.

Here are a few of our favorite film crew words:

Dolly: A wheeled cart that rides on tracks (basically, miniature railroad tracks). The camera crew uses the dolly to move the camera carefully through the scene, creating a smooth motion shot. The dolly carries the camera, the camera crew, and sometimes even the director.

Grip: Anybody in charge of adjusting or maintaining production equipment, especially camera equipment, such as dollies. The "key grip" is the leader of a group of grips.

Best Boy: The second-in-command for a particular technical team. For example, the Best Boy Grip is the second in command for a grip team. The term comes from early sailing and whaler speak - sailors would often get extra work setting up rigging and building theater sets, and they brought their special language with them.

Squib: A tiny explosive, generally used to represent a bullet hitting something. The special effects crew has to time squib detonations precisely so they correspond with the action in the scene. Squibs are sometimes combined with packets of fake blood to create gory gunshot wounds.

Gaffer: The head of the lighting/electrical crew. The term comes from the natural lighting system used in many early silent movies. In those days, the film crew would adjust lighting by opening and closing large flaps over skylight windows. They used long sticks, called gaffs, to adjust the flaps. Sailors, working as stagehands, took the term from a type of pole used on ships.

Boom Microphone: A microphone connected to a long pole. The boom operator holds the boom microphone over the actors in a scene to record the dialogue. A good boom operator will hold the boom microphone just out of view of the camera. Every once in a while, you'll see a film flub where the boom microphone dips into the scene.

Swing Gang: The team that builds and demolishes sets.

Dailies: Rough film prints, developed quickly after filming a scene. The director, crew and actors will watch dailies to make sure the acting and camera work were good in each shot.

Cowboy Shot: A shot showing an actor from mid-thigh up, commonly used in cowboy gunfight standoffs.

Breakdown Script: A list of every single actor, crew member, piece of camera equipment, costume and prop needed for a particular day of shooting.

Call Sheet: A list of all the actors required for each movie scene, with an estimate of when the director will need them.

Foley Artist: A sound mixer who records basic film sound effects, such as creaking doors, footsteps, and punches. The foley artist has to find a way to recreate each sound in the recording studio and then synch the sound effect with the action on the screen.