EventTarget.addEventListener()

The modern standard API for adding DOM event handlers. Introduced in the DOM Level 2 Events spec. Also implies support for `removeEventListener`, the [capture phase](https://dom.spec.whatwg.org/#dom-event-capturing_phase) of DOM event dispatch, as well as the `stopPropagation()` and `preventDefault()` event methods.

Media Queries: resolution feature

Allows a media query to be set based on the device pixels used per CSS unit. While the standard uses `min`/`max-resolution` for this, some browsers support the older non-standard `device-pixel-ratio` media query.

CSS overflow: overlay

The `overlay` value of the `overflow` CSS property is a non-standard value to make scrollbars appear on top of content rather than take up space. This value is deprecated and related functionality being standardized as [the `scrollbar-gutter` property](mdn-css_properties_scrollbar-gutter).

HEVC/H.265 video format

The High Efficiency Video Coding (HEVC) compression standard is a video compression format intended to succeed H.264. It is hard for browsers to universally support HEVC because it is [complex and expensive to license](https://en.wikipedia.org/wiki/High_Efficiency_Video_Coding#Patent_licensing). HEVC competes with [AV1](/av1) which has similar compression quality and provides a free license.

HTTP/2 protocol

Networking protocol for low-latency transport of content over the web. Originally started out from the SPDY protocol, now standardized as HTTP version 2.

HTTP/3 protocol

Third version of the HTTP networking protocol which uses QUIC as transport protocol. Previously known as HTTP-over-QUIC, now standardized as HTTP/3.

Resource Hints: Lazyload

Gives a hint to the browser to lower the loading priority of a resource. Please note that this is a legacy attribute, see the [`loading`](/loading-lazy-attr) attribute for the new standardized API.

Element.scrollIntoViewIfNeeded()

If the element is fully within the visible area of the viewport, it does nothing. Otherwise, the element is scrolled into view. A proprietary variant of the standard `Element.scrollIntoView()` method.

CSS -webkit-user-drag property

The non-standard `-webkit-user-drag` CSS property can be used to either make an element draggable or explicitly non-draggable (like links and images). See the standardized [draggable attribute/property](/mdn-api_htmlelement_draggable) for the recommended alternative method of accomplishing the same functionality.

zstd (Zstandard) content-encoding

Data compression method providing faster page loading while using less CPU power on the server.

oes_standard_derivatives api

css property: dynamic-range-limit: standard

javascript built-in: evalerror

javascript built-in: rangeerror

javascript built-in: referenceerror

javascript built-in: syntaxerror

javascript built-in: typeerror

javascript built-in: urierror

css max-lines property

empty tag syntax: <>