Chunk overlap repeats some text at the boundary between neighboring chunks. It reduces the chance that a sentence, definition, or important relationship is split so neither chunk contains enough context.
Overlap can improve retrieval, but it increases embedding cost, storage, and duplicate results. Too much overlap may fill the final prompt with repeated evidence and reduce source diversity.
Use the smallest overlap that fixes measured boundary failures. Structural chunking may need less overlap because headings and paragraphs already create meaningful boundaries. Deduplicate or merge adjacent retrieved chunks before generation, and evaluate overlap with real queries rather than selecting a percentage by habit.
Rewriting in plainer words…
This answer doesn't lend itself to a diagram - it reads best . No credits were charged.
