# Progressive enhancement

Canonical HTML: /atlas/progressive-enhancement
Atlas version: atlas-2026-07-28-v1
Category: Rendering and client execution

## Definition

Progressive enhancement starts with functional HTML and layers richer behavior on top.

## How it works

Links remain links, forms remain forms, and content remains text. Scripts can improve speed or interaction without becoming the sole route to the information.

## How to validate it

Test the same task with scripts blocked, slow, and fully enabled; the destination and essential facts should remain available in every mode.

## Common failure

A styled button with only an onclick handler is not an enhanced link; it is a separate JavaScript-only interface.

## Related topics

- [Hydration](/atlas/hydration)
- [Client-rendered content](/atlas/client-rendering)