Baseline (compatibility)
Baseline identifies widely-supported web platform features. Web developers can expect Baseline features to work in contemporary browsers.
A Baseline feature - such as an API, a set of CSS properties, or a JavaScript syntax - is known to work consistently in at least one version before the current version of all of several well-known browsers (Chrome, Edge, Firefox, and Safari).
Badges
🟢 If you see the green Baseline badge, then you can trust that the feature will work in the browsers' latest and previous major releases.
🟡 If you see a yellow badge showing that a feature is not yet Baseline, then do more research and testing with your site's users before relying on that feature, or wait for it to become Baseline.
Extra considerations
Baseline is a summary guide to support and doesn't cover every situation. If your site needs to work with a browser's long-term support release, an older device or browser release, or a browser not covered by the Baseline report, then you may need to do your own research or testing. If Baseline doesn't cover your situation, then consider reading browser compatibility tables on MDN or visiting caniuse.com before committing to a feature.
Contributing
Baseline is a community effort of the W3C WebDX Community Group and relies on MDN's open source browser compatibility data. If you have questions, feedback, or want to help update and expand the features covered by Baseline status reports, then go to web-platform-dx/feature-set to participate.