The term "chapter" can refer to various contexts, so I'll provide answers for some common ones:

• Fortnite Chapter 6 Season 3 ended on August 8, 2025, and Chapter 6 Season 4 started immediately on that day. So, chapters in Fortnite are marked by seasonal changes with specific start and end dates.

• In writing or storytelling, a chapter starts and finishes when a short story or a narrative segment reaches a natural conclusion. Each chapter should have a clear goal or focus for the characters or story elements involved.

• For Genshin Impact, chapters refer to major parts of the Archon Quest storyline set in different nations within the game's world. For instance, Chapter III is set in Sumeru, and Chapter IV in Fontaine, but specific release or event dates depend on the game's update schedule.

If you meant a specific "chapter" in another context, please clarify for a more precise answer.