Definition
A web development strategy that delivers a baseline experience to all browsers first, then layers advanced styling and scripting only where supported—ensuring core content and functionality remain accessible regardless of device or browser capability.
Why It Matters
Over-reliance on “all-or-nothing” tech stacks leaves users on slow networks, old devices, or high-latency connections in the dark. Ignoring PE creates fragile systems where a single network glitch or missing polyfill results in a blank screen and total loss of service. It is the ethical choice for global accessibility and the technical choice for maximum system uptime.
Core Concepts
- HTML Layer: Meaningful semantic markup in logical order supports accessibility and SEO even without CSS/JS.
- CSS Layer: Older browsers ignore unknown properties; newer browsers render gradients, flexbox, and grid.
- JavaScript Layer: Core navigation and forms must work with JS disabled; enhancements add convenience.
- Contrast with Graceful Degradation: PE builds up from a minimum; GD builds down from a maximum experience.