The JPEG image format is a raster graphics file format with lossy compression.

The <input type="file" multiple> HTML element shows a file picker from which users can choose one or more files to upload with a form.

The Worker() constructor runs a script in its own thread, which can send and receive messages with the script that created it. Also known as web workers.

The visible property of the window.locationbar, window.menubar, window.personalbar, window.scrollbars, window.statusbar, and window.toolbar APIs historically represented the visibility of a browser user interface. For privacy reasons, it now represents whether the window is a pop-up.

The contenteditable global HTML attribute allows the user to edit the content of an element, such as inserting or deleting text.

The style global HTML attribute applies inline CSS styling declarations to individual elements.

The window.matchMedia() method checks whether a media query applies to the document.

The window.screen property contains information about the screen of the output device that the referenced window is being rendered on.

The accesskey global HTML attribute gives a hint for generating a keyboard shortcut for the current element. The attribute value must consist of a single printable character.

The change event for <input>, <select>, and <textarea> elements fires when the user modifies the element's value. Unlike the input event, the change event does not necessarily fire on every alteration to an element's value.

The lang global HTML attribute defines the language of an element. It's used by assistive technology to correctly read the content, translation tools to select the origin language, and other applications.

The title global HTML attribute sets information about an element, such as a name or description. The value is typically shown as a tooltip that appears on mouse over. Since it's not often available to touch-only, keyboard-only, or assistive technology users, it's not a substitute for other text.

Focus events, such as focus and blur, fire when an element gets or loses focus.

The background-size CSS property scales or stretches a background based on the size of the element (with the contain and cover keywords), a length, or percentage.

The keydown and keyup events fire for each key press (or, with modifier keys, a combination of key presses) on a keyboard.

The color CSS property sets the primary foreground color of an element, which is used for text, the default border color, and text decorations.

The <dl>, <dt>, and <dd> HTML elements represent a list of terms and their associated descriptions. Use a description list to create glossaries or similar list of key-value pairs.

The pointer-events CSS property sets whether a user can interact with an element using a mouse, touch, or other pointing input device.

CSS selectors match elements based on their type, attributes, and relationship to other elements. They define the specific elements to which a block of styles will be applied. This feature represents the oldest selectors of CSS.

The Event API and the addEventListener() method on objects that receive events (event targets) represent and handle significant things happening on a page. Many APIs fire events for a wide range of situations relating to those APIs, such as an image loading, a user clicking, or a value changing.

The window.alert(), window.confirm(), and window.prompt() methods open modal dialogs for notifying the user, asking for confirmation, or entering text.

The Set-Cookie HTTP header stores limited amounts of data that persist across request and response, creating shared state between the browser and server.

Cross-Origin Resource Sharing is an HTTP-header based mechanism that allows a server to indicate any origins (domain, scheme, or port) other than its own from which a browser should permit loading resources. Also known as CORS.

Objects in JavaScript are collections of key-value pairs.

The window global object represents a browser tab or iframe and its relationship to the document and other tabs. It's also a generic global object, under which many other APIs are located.

Data URLs are URLs that start with the data: scheme and which directly contain data rather than point to remote resources.

The Authorization and WWW-Authenticate headers authenticate a user with a server.

The <input type="button"> HTML element represents a button that triggers some action, such as submitting a form or opening a dialog, styled as a labeled rectangular box by default. Not to be confused with the <button> element, which contains HTML content.

The <input type="checkbox"> HTML element represents a tickable box with two states, checked and unchecked.

The <input type="file"> HTML element shows a file picker from which users can choose a file to upload with the form.