On "Seinfeld," George insists that the NBC pilot should be a show about nothing. His deliberately unconventional idea is that the program should portray ordinary conversations and everyday events without a traditional plot or central subject.
George develops the concept while he and Jerry are trying to create a series for NBC. A conversation about confusing "seltzer" and "salsa" inspires him to imagine a sitcom based on the random discussions Jerry has with George, Elaine, and Kramer. George argues that the absence of a conventional premise is itself the premise.
The phrase is commonly associated with the entire real-life series, but in the episode it is specifically George's pitch for the fictional show they are proposing. The executives are skeptical, and George becomes so defensive about his artistic vision that he walks out of the meeting. Jerry nevertheless remains interested in pursuing the deal.
The storyline is a fictionalized version of how Jerry Seinfeld and Larry David developed a sitcom around observational comedy and mundane daily life. The concept later became one of the defining descriptions of "Seinfeld," though the series contains many elaborate plots and recurring storylines.