The personal wiki concept goes back to Ward Cunningham's original wiki in 1995. It distinguishes itself from notebooks (which are linear) and bookmarks (which are flat) by emphasising bidirectional links between concepts. A reader who maintains a personal wiki for a year can typically retrieve information they encountered six months ago — something neither bookmarks nor a notes app reliably support.

Modern personal wiki tools fall into three buckets: **manual-authored** (Obsidian, Roam Research, Notion), **highlight-based** (Readwise Reader), and **source-grounded auto-built** (Pith). The trade-off is between authoring effort and findability: manual wikis are highest-fidelity but require constant maintenance; auto-built wikis sacrifice some fidelity for zero-effort upkeep.