Digital On-screen Graphic
A Digital On-Screen Graphic is a watermark-like station logo that many television broadcasters overlay over a portion of the screen-area of their programmes to assist viewers in identifying the channel. They are thus a form of permanent visual station identification, increasing brand recognition. It also identifies the source of programming even if it is time-shifted (recorded to videotape, DVD, or via digital personal video recorder such as TiVo).
In the United Kingdom, Digital On-Screen Graphics are commonly known by the acronym DOG or the expanded acronym DOG tag.
In North America, they are known as bugs.
In the UK, DOGs were first used on satellite and cable television systems in their early days, when broadcasts were unmarked in the bouquet.
On British digital systems such as Sky Digital and Freeview, where channels have a set EPG number and a name displayed across the top of the screen when changing channel, large or intrusive DOGs have been deemed unnecessary by most users. The most notable case of user pressure over a DOG was BBC Four, who reduced their large, purple DOG to a small, transparent grey one, and moved it from the bottom left to the top right, after serious complaints from users.
Many news broadcasters place a clock alongside their DOG, giving it legitimacy if it is moved into an unorthodox position, such as the bottom left. In the United States, Canada, Australia, and New Zealand, DOGs may also include the show's parental guideline rating.