Browsers send the Save-Data HTTP request header when the user turns on a data-saving mode. It is a hint to reduce data sent to the browser. Servers should respond with alternative content, such as smaller images and videos, or different markup and styling.

The navigator.mediaDevices.getDisplayMedia() method asks the user to choose a screen or portion of a screen (such as a window) to capture as a media stream.

The :past and :future CSS pseudo-classes match prior or upcoming text track cues during media playback.

The navigator.vibrate() method makes a tactile alert, if the device is equipped with a haptic motor.

The Web Bluetooth API enables selecting and communicating with nearby Bluetooth devices.

The WebUSB API exposes USB compatible devices to web pages.

The navigator.xr API represents the browser's virtual reality or augmented reality system. You can use to request a WebXR session.

The alignment-baseline CSS property sets which baseline of an element is aligned with the corresponding baseline of its parent.

The beforeinstallprompt event fires when a Progressive Web App (PWA) is installable. You can cancel the event and later call event.prompt() to control when the installation prompt is shown. The appinstalled event fires when the PWA is successfully installed.

The clip CSS property sets the visible area of an absolutely positioned element.

The controlslist attribute for <audio> or <video> hides parts of the browser's built-in controls. For example, controlslist="nofullscreen" removes the button to play the video in fullscreen.

The paint() CSS function creates a custom image, drawn using a paint worklet, for an element's background or border.

The navigator.registerProtocolHandler() method declares a site's ability to handle an address scheme (also known as a protocol). For example, an email site can register to open mailto: URLs or a VoIP site to open tel: URLs.

The requestIdleCallback() API queues a function that runs in idle browser time, either at the end of a frame or when the user is inactive. Also known as the background tasks API.

The resize CSS property sets whether an element can be resized by the user, and on which axes.

The text-decoration: blink CSS declaration flashes text between visible and invisible.

The text-size-adjust CSS property disables or modifies the browser's default text size adjustment for small screen sizes.

The word-break: break-word CSS declaration sets word breaks to occur according to their customary rules.

The <input type="color"> HTML element shows a color picker from which users can choose a color value.

The s identifier in a CSS attribute selector matches attribute values case-sensitively in document languages like HTML where attribute values are case-insensitive.

The WebDriver protocol allows out-of-process programs to inspect and control browsers to, for example, run tests of web applications. Also known as WebDriver classic.

The touched property of a GamepadButton object indicates whether a button capable of detecting touch is currently touched.

The ::selection CSS pseudo-element selects text a user has highlighted.

The navigator.connection API provides information about the network connection a device is using and fires events when the connection type changes.

The ping attribute for <a> elements sets a URL to send a POST request to when the <a> is clicked. This is typically used for outbound link reporting.

The PaymentRequest API prompts the user to make a payment through the browser's user interface.

The speak-as CSS property sets how any element's content is spoken. Not to be confused with the speak-as descriptor of @counter-style at-rules.

The <input type="month"> HTML element shows a month picker.

TLS 1.3 sessions may be resumed more quickly by sending so-called early data to servers before the TLS handshake has finished. Also known as zero round-trip time resumption or 0-RTT.

The hand and pose properties of a Gamepad object represent the position in space and the hand that WebVR controllers are held in.