128-bit SIMD (Single Instruction Multiple Data) performs one instruction on multiple units of data, when running on hardware that supports such instructions. Also known as vector instructions.

The font-synthesis-small-caps CSS property sets whether or not the browser should synthesize small caps typefaces when they're missing from the font.

The font-synthesis-style CSS property sets whether or not the browser should synthesize italic and oblique typefaces when they're missing from the font.

The font-synthesis-weight CSS property sets whether or not the browser should synthesize bold typefaces when they're missing from the font.

Custom elements may act like built-in form elements, via the attachInternals() method of HTMLElement and the ElementInternals API.

The assign() method for <slot> elements assigns nodes to the slot, as an alternative to using the slot and name HTML attributes. The nodes must be children of a shadow host and the shadow root must be created with the slotAssignment set to "manual". Also known as manual slot assignment.

A <script type="importmap"> HTML element provides an import map as a JSON string. An import map controls how the browser should resolve module specifiers when importing JavaScript modules.

The range syntax of CSS media queries allows you to use mathematical comparison operators such as <, >, <=, and >= to define a range of values for a media query. For example, (400px < width < 1000px) returns true if the viewport width is between 400px and 1000px.

The messageerror event fires on a target, such as a window or worker, when an incoming message cannot be deserialized. This event can fire for many types of messages, such as cross-document messages or broadcast channel messages.

The OffscreenCanvas API provides a canvas that can be drawn to off screen, with no dependencies on the DOM, which can be used to run heavy rendering operations inside a worker context.

The Push API subscribes to and receives server-initiated messages. Subscribers receive pushed messages in the background, even after periods inactive or offline.

The screen.orientation API gets information about the orientation of the viewport, such as landscape or portrait. With this API, you can adapt an application's layout or behavior in response to changes in orientation.

The serverTiming property of a resource performance entry contains server timing information about network requests.

The translate HTML attribute marks whether an element's text should be translated.

The font-variant-alternates CSS property, along with the @font-feature-values at-rule, chooses when to use a font's alternate glyphs.

The sin(), cos(), tan(), asin(), acos(), atan(), and atan2() CSS functions compute various trigonometric functions.

The color-gamut media query sets styles based on the colors a device can display.

Container size queries with the @container (…) at-rule apply styles to an element based on a dimension of its container, such as width or height.

MathML, or the Mathematical Markup Language, describes mathematical notation, such as expressions and formulas. Also known as MathML Core.