Leaflet is a client-side JavaScript mapping library, currently at 2.0.0-alpha.1. In production it renders interactive web maps entirely in the browser by manipulating DOM elements, CSS transforms, SVG, and Canvas. The source is organized as an ES module library: `src/Leaflet.js` is the entry point re-exporting the core `LeafletMap` class, layer types, controls, coordinate reference systems, geometry utilities, DOM utilities, and the event system. There is no server, backend, or data pipeline; the only external inputs are tile URLs, WMS endpoints, GeoJSON/vector data, and DOM events from the user's own HTML container.