Opening Themes

Opening Themes are music videos that are played during the opening credits of a show, they are called as such because they carry a theme for that particular show. In many shows in an anime, opening themes are often changed when they get to a certain point of the series, like when a previous story arc has been finished and a new arc begins, the change of the opening theme will often correspond to the change of the ending theme as well but that there are always exceptions to this.