1. Audio element

    Method of playing sound on webpages (without requiring a plug-in). Includes support for the following media properties: `currentSrc`, `currentTime`, `paused`, `playbackRate`, `buffered`, `duration`, `played`, `seekable`, `ended`, `autoplay`, `loop`, `controls`, `volume` & `muted`

  2. AVIF image format

    A modern image format based on the AV1 video format. AVIF generally has better compression than [WebP](#feat=webp), JPEG, PNG and GIF and is designed to supersede them.

  3. CSS revert value

    A CSS keyword value that resets a property's value to the default specified by the browser in its UA stylesheet, as if the webpage had not included any CSS. For example, `display:revert` on a `<div>` would result in `display:block`. This is in contrast to the `initial` value, which is simply defined on a per-property basis, and for `display` would be `inline`.

  4. Data URIs

    Method of embedding images and other files in webpages as a string of text, generally using base64 encoding.

  5. PNG favicons

    Icon used by browsers to identify a webpage or site. While all browsers support the `.ico` format, the PNG format can be preferable.

  6. SVG favicons

    Icon used by browsers to identify a webpage or site. While all browsers support the `.ico` format, the SVG format can be preferable to more easily support higher resolutions or larger icons.

  7. Custom protocol handling

    Method of allowing a webpage to handle a given protocol using `navigator.registerProtocolHandler`. This allows certain URLs to be opened by a given web application, for example `mailto:` addresses can be opened by a webmail client.

  8. Signed HTTP Exchanges (SXG)

    Part of the Web Packaging spec, Signed HTTP Exchanges allow a different origin server to provide a resource, and this will be treated as if it came from the original server. This can be use with AMP CDNs, for example, to allow the original URL to be displayed in the URL bar.

  9. Video element

    Method of playing videos on webpages (without requiring a plug-in). Includes support for the following media properties: `currentSrc`, `currentTime`, `paused`, `playbackRate`, `buffered`, `duration`, `played`, `seekable`, `ended`, `autoplay`, `loop`, `controls`, `volume` & `muted`

  10. WebP image format

    Image format (based on the VP8 video format) that supports lossy and lossless compression, as well as animation and alpha transparency. WebP generally has better compression than JPEG, PNG and GIF and is designed to supersede them. [AVIF](#feat=avif) is designed to supersede WebP.

  11. X-Frame-Options HTTP header

    An HTTP header which indicates whether the browser should allow the webpage to be displayed in a frame within another webpage. Used as a defense against clickjacking attacks.