What is File-Based Routing?
Pages defined by file location: `+page.svelte` renders, `+layout.svelte` wraps, `+server.js` serves data. The route tree is the app map — no separate router config to drift.
Related terms
Load Function
Server-side data loading for a route before it renders. Load on the server for content crawlers and users need immediately; reach for client fetching only for interactive extras.
Form Actions
Progressive-enhancement mutations: forms that work without JavaScript and upgrade with it. The default for generated app mutations — resilient and accessible by construction.
Server Endpoint (+server.js)
The privileged layer for webhooks, secrets, and server-only logic. Anything touching keys, tokens, or private APIs lives here — never in components.
Svelte Runes
The `$state`, `$derived`, `$effect`, and `$props` primitives powering Svelte 5 reactivity. Runes are mandatory in generated code: explicit, compilable, and consistent across every component.
Hooks (hooks.server.js)
The request gate for sessions, auth, and cookies across routes. Centralize identity checks here instead of repeating them per page.
SSR vs CSR & Hydration
Server rendering delivers complete HTML fast; client rendering builds it in the browser; hydration animates the server HTML into an interactive app. Content pages render on the server by default.