Literature: What are the main differences between major supporting details and minor details when it comes to reading a passage and give example for it?

Answer 1

Major supporting details will usually move the plot forward in literature, whereas minor details may provide context and/or embellishment to support the plot/characters at that time.

For example, in Harry Potter and the Sorcerer's Stone, Harry's scar hurts the first time he sees Professor Snape in the Great Hall at Hogwarts. The major supporting detail in this passage is that Professor Snape is talking to Professor Quirrell at the time. We know through reading the rest of the book that Harry's scar hurts when Voldemort is near/angry. The detail describing Snape talking to Quirrell when Harry's scar hurts moves the plot forward because the detail is brought up again at later points in the book (and series), and serves as a fixed point of reference for character decisions.

Comparatively, a minor detail in Harry Potter would be something like the description of the Gryffindor common room. The picture painted in the reader's mind is vivid and beautiful, but it ultimately doesn't serve to advance the plot. It helps you understand and get a feel for the setting (e.g., "big squashy armchairs next to a roaring fire"), but the details provided don't add anything to character motives, major events, etc.

To recap: a detail like Harry's scar hurting, which happens frequently and serves as a catalyst for Harry's decision-making and moving the plot forward, is a major supporting detail. A description of the Gryffindor common room, while vivid and scene-setting, could be replaced by another scene description (or house common room in the Harry Potter universe) and the plot/character choices would likely still be the same.