The <small> element represents side-comments and small print, like copyright and legal text, independent of its styled presentation. Styled in a reduced font size by default.

The <source> element sets a media resource for the <picture>, <video>, and <audio> elements.

The <span> HTML element is the generic inline container for content.

The <strong> HTML element brings attention to the content, styling text as bold by default.

The <style> element embeds an inline CSS stylesheet in a document.

The <sub> and <sup> elements sets inline text to be displayed as subscript or superscript for solely typographical reasons.

The <textarea> element represents an editing control that allows users to enter multi-line, free-form, plain text.

The <title> element sets the title of the document and exposes it to users via the UI of the browser or app they're using and through assistive technology.

The <u> HTML element makes non-textual annotations, styling text as underlined by default.

The <var> element represents the name of a variable in a mathematical expression or a programming context.

The <video> element plays videos or movies, optionally with controls provided by the browser.

The <wbr> HTML element represents a word break opportunity, to explicitly mark a place within a word where a line might be broken.

The @charset CSS at-rule specifies the character encoding of an external style sheet.

The @import CSS at-rule loads styles from another stylesheet.

The @namespace CSS rule sets a default namespace or namespace prefix. Namespace prefixes allow CSS selectors to distinguish elements with the same name but different document types, such as the HTML <a> element and the SVG <a> element.

The position: absolute CSS declaration removes an element from the normal flow and positions it relative to its containing block, which is often the root element, or closest positioned ancestor.

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

Arrays are ordered lists of JavaScript values.

Array iteration methods

The array splice() method changes an array in-place. You can use it to delete items, overwrite items, or insert items, starting from an index.

The Array.isArray() static method checks whether a value is an array.

The BMP image format is an uncompressed raster graphics file format. Also known as a bitmap.

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 border CSS property sets the color, style, and width of the line around an element.

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.

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

The console API logs debugging messages to the browser development tools' console.

The content CSS property sets the content inside of an element or pseudo-element, replacing the current value. It's often used with the ::before and ::after pseudo-elements to generate cosmetic content.

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