A cutscene is a time in a video game where the game stops and the player watches something happen.
Usually cutscenes tell part of the story, such as showing characters talking or having a narrator say what is going on. Sometimes, however, a cutscene just shows something that is happening in the game, like a boss showing up, a ship taking off, or a building falling down.
There are many different types of cutscene. Some cutscenes are very simple and just show pictures with text like a slideshow. Others may be animated like a cartoon. Sometimes the cutscene appears directly in the game engine.
Many new games use prerendered scenes, meaning that the scene was created when the game was made and saved as a video file. Prerendered videos are sometimes just saved movies of things recorded in the game engine, but some use Computer-generated imagery (CGI), which is separately made 3D graphics which are usually fancier than the game's normal graphics. Prerendered scenes with CGI are often used for a game's intro video.
A few games use live-action video footage, which is filmed like a movie or television show. Sometimes live-action footage will be used together with CGI.