on Writing Forward:

Chapters, scenes, and sequences are structural units of storytelling. These are the basic blocks of a story that contain all other elements, from characters, plot, and setting to action, dialogue, and description.

Chapters are units within a book that are named, numbered, or both. Chapters provide numerous functions: they break a story into digestible components; they provide transitions between moments in time, locations, or points of view; and they provide a novel with structure.

There are no rules regarding chapter length. Some chapters are short; others are long. Some novels contain chapters that are all roughly the same length; others contain chapters that vary in length. The length of a story’s chapters is driven by the story and the author’s judgment. However, chapter length should be comfortable and flow with the story’s pacing.

Similarly, there are no rules regarding when to start or end a chapter. Some chapters end on cliffhangers, which keep readers turning the pages. Some chapters wrap up neatly, providing pauses within a story.

A chapter can be comprised of a single scene, but it can also contain multiple scenes.