`<main>` wraps the unique-to-this-page content (screen readers jump to it with a keyboard shortcut). `<aside>` is supporting / tangential content — sidebars, callouts, related links.
Standard site footer with grouped links, brand block, social icons, and legal/copyright. Use semantic `<nav aria-label>` on each column so screen readers announce the section labels.
Compose's three fundamental layouts. `Column` stacks vertically, `Row` horizontally, `Box` overlays. Combine with `Modifier.weight()`, alignment, and arrangement for flexible UIs.