what is a filler episode

A filler episode is an episode in a TV series that is unrelated to the main plot and does not significantly alter the relations between the characters. Filler episodes are used by anime and other TV shows, usually between the individual plot points of the major arcs, or between the end of a major arc and the beginning of another one. Sometimes entire arcs are filler episodes. Filler episodes are created to buy time for the manga to create more content, to keep the show airing on schedule, or to create more depth to characters, exploring the interactions between characters, sometimes out of competitions and battles and in more mundane settings. Filler episodes can be one-offs or entire arcs of collected episodes. They can be hard to identify until its too late, but there are websites like Anime Filler List that can help identify them. Filler episodes are not always bad and can be great opportunities for side characters to take the spotlight.