warm-up; pre-show talk
Entertainment-industry term for the warm-up talk or performance given to the audience before the main act or TV recording begins, often by a comedian or announcer.
Before the recording, they warm up the audience with a pre-show talk.
General sense of an introductory talk or explanation, similar to a prologue. Less common than the entertainment-specific sense.
In the introduction to the lecture, they explained the background of the theme.
Compound of 前 (まえ, 'before') and 説 (せつ, 'explanation' or 'opinion'), literally 'pre-explanation'. The term is primarily used in the Japanese entertainment industry.