Imagine the UX possibilities if the browser could easily tell what is a payment form. Or a next/previous button. Or a div full of nav. Fathom is a Mozilla-developed domain-specific language for identifying such entities, making the expression of how-do-you-find-it rules concise, declarative, low-state, and extensible. It combines CSS selectors, structure-sensitive clustering, typed annotations, fuzzy scoring, and an optimizer to make it all fast. Needing nothing but JS, it's already running in add-ons, on the server side, and on iOS and Android. Join us for a tour, and see how you can extract your own meaning from the web.