A "fade-in" is a gradual transition effect used in film, video, and audio production. It starts with a black screen or silence and slowly increases the visibility or volume of the content. This technique helps to create a smooth introduction to a scene or sound, making it less abrupt and more engaging for the audience. In visual media, a fade-in often accompanies the beginning of a movie or television show, setting the tone for what follows. In audio, it can enhance the listening experience by gently introducing a musical track or narration, allowing the audience to acclimate to the sound.