Continuity
Canon
The works and facts widely considered official or authoritative within a fictional world, as distinct from fanon and headcanon.
Canon is "the body of works taking place in a particular fictional world that are widely considered to be official or authoritative," especially those by the original author or creator. Who decides is contested: "There is no consensus regarding who has the authority to decide what is or is not canonical." Star Wars rebranded its pre-2014 Expanded Universe as the non-canonical "Legends," while Doctor Who deliberately avoids canon pronouncements altogether. Widely accepted fan ideas are fanon; an individual fan's interpretation is headcanon.
For the working writer, canon is the set of facts the story itself has established, and every later chapter gets read against it. A deliberate change is a retcon; an accidental contradiction is a plot hole. Managing canon while writing is the core job of the story bible.