Progressive summarization

Progressive summarization is a way of distilling saved material in layers, each one smaller than the last, so a note can be understood at a glance months later without rereading it all. Tiago Forte described it as part of his Building a Second Brain approach. The layers are:

1. Layer 1: the saved material itself, already trimmed to the passages worth keeping.
2. Layer 2: the best of those passages in bold.
3. Layer 3: the best of the bold in ==highlight==.
4. Layer 4: a short executive summary in the person's own words, at the top.

The method works because it spreads effort over time: each layer is added only when the note is used again, so only notes that keep proving useful get the full treatment. A later reader can stop at whichever layer gives them enough.