What does it mean that progressive disclosure through hierarchy?

Good hierarchies let people see the big picture first and drill into detail on demand.

Example: A 200-page technical architecture document sits unread on a shared drive. Nobody has time. Now restructure it: a one-paragraph executive summary at the top, five section headings with two-sentence abstracts, and the full detail behind each heading. The same information, but now a VP reads the summary in 30 seconds, a tech lead reads the section they own in 5 minutes, and an engineer drills into the appendix for implementation specs. Nothing was removed. The hierarchy decided what gets seen first.

Try this: Pick a document, note, or project plan you own that's longer than one page. Create three layers: Layer 1 — a single sentence that captures the whole thing. Layer 2 — one paragraph per major section (3-5 sections). Layer 3 — the full detail, accessible but not forced on anyone. Read only Layer 1 aloud. Does it stand on its own? If not, your hierarchy isn't encoding the right priorities at the top.