A serial film, film serial (or just serial), movie serial, or chapter play, is a motion picture form popular during the first half of the 20th century, consisting of a series of short subjects exhibited in consecutive order at one theater, generally advancing weekly, until the series is completed. Usually, each serial involves a single set of characters, protagonistic and antagonistic, involved in a single story. The film is edited into chapters, after the fashion of serial fiction, and the episodes should not be shown out of order, as individual chapters, or as part of a random collection of short subjects.
Each chapter was screened at a movie theater for one week, and typically ended with a cliffhanger, in which characters found themselves in perilous situations with little apparent chance of escape. Viewers had to return each week to see the cliffhangers resolved and to follow the continuing story. Movie serials were especially popular with children, and for many youths in the first half of the 20th century a typical Saturday matinee at the movies included at least one chapter of a serial, along with animated cartoons, newsreels, and two feature films.