Since the early days of television, such listings have been printed in local newspapers, newspaper inserts, or magazines (including specialized listings magazines), but are now often viewed as electronic program guides available on set-top boxes and most digital TV sets.
Most print listings publications originally displayed programming information a text-based format modeled after program logs maintained by local broadcasters, which organized programs first by their scheduled airtime and secondarily by channel, a format that allowed complete program titles and synopses of reasonable detail to be incorporated into the guide. With the formation of other broadcast and subscription channels in subsequent years, set space requirements resulted in detailed synopses being gradually restricted to series and specials – usually, those airing in evening timeslots – as well as movies.
Since the 1980s, grids – which organize listings primarily by channel in correspondence to airtime – have become the common format for displaying listings information, as it allows more space to display programming data for an expanded lineup of channels. Many national and local TV listings magazines (such as TV Guide in the United States) originally incorporated grids to show prime time listings, but would eventually begin expanding them to encompass the full broadcast day during the late 1980s and 1990s. For print publications, space requirements have largely limited the availability and detail of programming information that can be incorporated into a grid format; however, because web- and application-based APIs can fit more information into such a structure, the format does allow for detailed synopses to be included into a grid. However, most websites and mobile apps offering program listings usually incorporate synopses and other information concerning a specific television program in a clickable or swipeable dialog box.