Reading about Byzantine fault tolerance, I hit 'Lamport timestamps' in paragraph two. I knew roughly what they were. Not well enough. I opened a new tab, read half the Wikipedia entry, came back, and had lost the thread of the original article entirely. rabbitholes is a Chrome extension that renders an explanation next to your cursor the moment you highlight text — no new tab, no context switch. The tooltip runs in a shadow DOM so it doesn't touch the host page's styles or layout. The part I use most: every word in the explanation is itself clickable. Highlight 'Lamport timestamps,' read the explanation, see 'vector clocks' in the response, drag across it, get another layer. The extension tracks how many hops deep you've gone, and if you end up at philosophy — you usually do — it shows you the full trail. When the inline explanation isn't enough, a globe icon re-runs the query enriched with Brave Search results, with source chips in the tooltip.…