Filmmaking requires precision teamwork, and each credit is well earned.
In movie language, a gaffer is the chief electrician; it evolved from the German word granfer, meaning “grandfather.”
A grip requires strength, because he or she builds and dismantles scenery and handles other physical chores that require a strong grip.
A best boy is the gaffer’s or grip’s assistant.
Credits for the gaffer, the key grip, and the best boy are usually shown at the end of a movie.