Short answers, pulled from the story.
A story arc is the chronological construction of a plot that moves a character or situation from one state to another. In television, it refers to an extended or continuing storyline that unfolds over multiple episodes; in a traditional Hollywood film, it usually follows a three-act structure.
One of the first recorded uses of the term appeared in 1973 in Time Magazine, in a synopsis of the film The Friends of Eddie Coyle. The review praised how the director maintained pacing while developing his story's arc.
Webcomics are more likely to use story arcs than newspaper comics because their online archives allow new readers to start from the beginning and follow the continuity. Newspaper strips reach readers who may have missed prior installments, making sustained arcs a commercial risk most strips avoided.
Arc-based series like V were often short-lived and had difficulty attracting new viewers because the story depended on continuous viewing from the start. The rise of DVD box sets and streaming later worked in their favor by making complete seasons easy to access in order.
Most manga and anime series shorter than twenty-six chapters are a single arc spanning all chapters, making individual episodes confusing when watched in isolation. Longer series such as Bleach, One Piece, and Naruto contain multiple arcs, while Dragon Ball Z adapts four distinct arcs from the Dragon Ball manga, each with its own ultimate antagonist.
The monomyth is a theory of storytelling developed by Joseph Campbell in his book The Hero with a Thousand Faces. Christopher Vogler adapted the same theory for western storytelling in The Writer's Journey: Mythic Structure for Writers, and it describes a pattern of transformation that aligns with the arc structure's core purpose of moving a character from weakness to strength.