In video terminology, when encoding in MPEG video GOP is the abbreviation for Group Of Pictures. In a motion sequence, GOPs are individual frames of pictures that are grouped together and played back so that the viewer registers the video's spatial motion. The GOP allows editing and splicing of video material from different sources to allow for rapid forward or reverse searching through sequences. An Open GOP will contain some references from the previous GOP. A GOP is called a Closed GOP when either there are no B_pictures immediately following the first I_picture or such B_pictures haven't any references coming from the previous GOP.