What is "cold open"

n. (context television English) A teaser segment shown before the opening credits.

A cold open (also called a teaser) in a television program or movie is the technique of jumping directly into a story at the beginning or opening of the show before the title sequence or opening credits are shown. On television, this is often done on the theory that involving the audience in the plot as soon as possible will reduce the likelihood of their switching away from a show during the opening commercial.

The cold open technique is sometimes used in movies. There, "cold opening" still refers to the opening moments or scenes, but not necessarily to the full duration before the title card, as the title card might appear well after the cold open has been achieved.