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HTML and CSS are the backbone of web development, and it is essential for any web developer to have a good understanding of the key terms used in these languages. In this article, we will discuss the most important key terms in HTML and CSS with a brief description for each.

This will be a quick approach to revise and cover the entire domain of HTML and CSS.

HTML Key Terms:


Term	Description
HTML	Hypertext Markup Language (HTML) is the standard markup language used for creating web pages and web applications.
Tags	A markup element used to define the structure and content of a web page.
Attributes	A property of a tag that specifies additional information about the tag.
Element	A combination of a tag and its attributes.
Head tag	The part of an HTML document that contains information about the document, such as its title and metadata.
Body tag	The part of an HTML document that contains the visible content of the web page.
Meta tags	HTML tags used to provide metadata about the web page, such as the author, description, and keywords.
Paragraph tag	An HTML tag used to define a paragraph of text.
Heading tags	HTML tags used to define headings or subheadings.
Anchor tag	An HTML tag used to create a hyperlink to another web page or file.
Image tag	An HTML tag used to display images on a web page.
Alt attribute	An attribute used to specify alternative text for an image, which is displayed if the image cannot be loaded.
List tags	HTML tags used to create ordered or unordered lists.
Table tags	HTML tags used to create tables on a web page.
Table row tags	A tag used to define a row in an HTML table.
Table data tag	A tag used to define a cell in an HTML table.
Form tag	An HTML tag used to create forms for user input.
Input tags	HTML tags used to create various types of form input fields, such as text boxes, radio buttons, and checkboxes.
Select tag	An HTML tag used to create drop-down menus in forms.
Option tag	An HTML tag used to define the options in a drop-down menu created with the select tag.
Label tag	An HTML tag used to associate text with a form input field.
Textarea tag	An HTML tag used to create a multi-line text input field.
Button tag	An HTML tag used to create clickable buttons on a web page.
Div tag	An HTML tag used to group and style other HTML elements.
Span tag	An HTML tag used to apply styles to small portions of text within a larger block of text.
Iframe tag	A tag used to embed another HTML document within the current document.
Noscript tag	A tag used to provide alternate content for users who have disabled JavaScript in their browsers.
Embed tag	A tag used to embed multimedia content, such as audio or video, in an HTML document.
Noembed tag	A tag used to provide alternate content for browsers that do not support embedded multimedia content.
Class attribute	An attribute used to specify a class for an HTML element, which can be used to apply styles to multiple elements.
ID attribute	An attribute used to specify a unique identifier for an HTML element, which can be used to target the element with CSS or JavaScript.
CSS (Cascading Style Sheets)	A stylesheet language used to style HTML documents.
Inline styles	CSS styles applied directly to an HTML element using the style attribute.
Internal styles	CSS styles defined within the head of an HTML document using the style tag.
External styles	CSS styles defined in a separate CSS file and linked to the HTML document using the link tag.
Selectors	CSS syntax used to target specific HTML elements for styling.
Descendant selector	A CSS selector used to target elements that are descendants of another element.
Class selector	A CSS selector used to target elements with a specific class.
ID selector	A CSS selector used to target elements with a specific ID.
Universal selector	A CSS selector used to target all elements on a web page.
Box model	A concept in CSS that describes how each HTML element is rendered as a rectangular box.
Margin	The space between an element's border and the surrounding elements.
Border	The edge of an element's rectangular box.
Padding	The space between an element's content and its border.
Height	The vertical dimension of an element's rectangular box
Width	The horizontal dimension of an element's rectangular box.
Display property	A CSS property that determines how an element is displayed on a web page, such as block, inline, or none.
Position property	A CSS property used to position an element on a web page, such as relative, absolute, or fixed.
Float property	A CSS property used to position an element to the left or right of its container.
Clear property	A CSS property used to prevent elements from floating next to a cleared element.
Box-sizing property	A CSS property used to determine how an element's width and height are calculated, such as content-box or border-box.
Media queries	CSS syntax used to apply different styles based on the size or orientation of the user's device.
Responsive design	A design approach that aims to create web pages that look good on any device, using techniques such as fluid layouts and media queries.
Accessibility	The practice of designing web pages that are usable by people with disabilities, such as those with visual or motor impairments.
Semantic HTML	The use of HTML elements that convey meaning beyond just their visual appearance, such as the header, main, and footer elements.
DOCTYPE	A declaration that specifies the version of HTML being used in the document.
Title attribute	An attribute used to provide additional information about an HTML element, such as a tooltip.
Rel attribute	An attribute used to specify the relationship between the current document and a linked document or resource.
Href attribute	An attribute used to specify the URL of a linked document or resource.
SEO (Search Engine Optimization)	The practice of optimizing web pages for search engines, such as by using appropriate meta tags, heading tags, and keywords.

CSS Key Terms:


Term	Description
CSS (Cascading Style Sheets)	A stylesheet language used to style HTML documents.
Selector	CSS syntax used to target specific HTML elements for styling.
Property	A characteristic of an HTML element that can be styled using CSS.
Value	The specific setting for a CSS property.
Style rule	A set of one or more CSS declarations applied to a selector.
Declaration	A single CSS property-value pair within a style rule.
Class	A group of HTML elements with a common class attribute that can be styled together using CSS.
ID	A unique identifier for an HTML element that can be targeted with CSS.
Pseudo-class	A keyword added to a selector that targets a specific state of an element, such as :hover or :active.
Pseudo-element	A keyword added to a selector that targets a specific part of an element, such as ::before or ::after.
Inheritance	The ability of child elements to inherit CSS properties from their parent elements.
Specificity	The hierarchy of importance for CSS selectors, used to determine which styles apply to an element.
Box model	A concept in CSS that describes how each HTML element is rendered as a rectangular box.
Margin	The space between an element's border and the surrounding elements.
Border	The edge of an element's rectangular box.
Padding	The space between an element's content and its border.
Height	The vertical dimension of an element's rectangular box.
Width	The horizontal dimension of an element's rectangular box.
Background	The color or image used for an element's background.
Color	The color of an element's text and other content.
Font	The typeface and other settings used for an element's text.
Text alignment	The horizontal alignment of an element's text, such as left, right, or center.
Line-height	The vertical spacing between lines of text in an element.
Display property	A CSS property that determines how an element is displayed on a web page, such as block, inline, or none.
Position property	A CSS property used to position an element on a web page, such as relative, absolute, or fixed.
Float property	A CSS property used to position an element to the left or right of its container.
Clear property	A CSS property used to prevent elements from floating next to a cleared element.
Visibility property	A CSS property used to hide or show an element on a web page.
Opacity property	A CSS property used to adjust the transparency of an element.
Transition	A CSS property used to create a smooth animation between two states of an element.
Animation	A CSS property used to create more complex animations for an element.
Flexbox	A layout mode in CSS used to create flexible and responsive layouts.
Grid	A layout mode in CSS used to create complex, two-dimensional layouts.
Media queries	CSS syntax used to apply different styles based on the size or orientation of the user's device.
Responsive design	A design approach that aims to create web pages that look good on any device, using techniques such as fluid layouts and media queries.
Responsive images	Techniques used to ensure that images are appropriately sized for the device they are being displayed on.
Vendor prefixes	Prefixes added to CSS properties to indicate that they are experimental or specific to a particular browser, such as -webkit- or -moz-.
Normalize.css	A CSS file that provides consistent default styles across different browsers.
SCSS (Sass)	A preprocessor for CSS that adds additional functionality, such as variables, nesting, and mixins.
LESS	A preprocessor for CSS that allows for dynamic styles and additional functionality.
PostCSS	A tool that transforms CSS with JavaScript plugins, allowing for additional functionality and improved browser support.
CSS modules	A system for organizing CSS in a way that avoids naming collisions and allows for better reuse.
BEM (Block Element Modifier)	A naming convention for CSS classes that helps to create more maintainable and scalable CSS code.
CSS frameworks	Pre-built CSS files and styles that can be used to quickly create a website or application.
Bootstrap	A popular CSS framework that provides pre-built styles and components for building responsive websites.
Materialize	A stylesheet language used to style HTML documents A CSS framework based on Google's Material Design principles.
Foundation	A responsive CSS framework that provides a flexible grid system and pre-built components.
Tailwind CSS	A CSS framework that provides pre-built utility classes for quickly building custom designs.
CSS preprocessors	Tools that generate CSS from higher-level syntax, such as SCSS or LESS.
CSS-in-JS	A technique that allows for writing CSS directly in JavaScript code, providing more dynamic and modular styles.
Foundation	A responsive CSS framework that provides a flexible grid system and pre-built components.
Max-height property	A property used to set the maximum height of an HTML element.
Min-height property	A property used to set the minimum height of an HTML element.
Background color property	A property used to set the background color of an HTML element.
Background image property	A property used to set the background image of an HTML element.
Font-family property	A property used to set the font of an HTML element.
@media rule	A rule used to apply different styles based on the size or orientation of the viewport.
@font-face rule	A rule used to specify a custom font to be used on an HTML page.
@keyframes rule	A rule used to define a set of styles to be used in an animation.
!important	A code used to override other style declarations and apply a particular style property and value.
Framework	A pre-built set of CSS and HTML files used to create a responsive and customizable website or web application.

In conclusion of this article at OpenGenus, HTML and CSS are two essential languages for creating websites and web applications. HTML provides the structure and content of a web page, while CSS is used for styling and layout. This list of key terms related to HTML and CSS provides a quick revision of important concepts, including elements, tags, attributes, selectors, properties, values, classes, IDs, and frameworks. By understanding these key terms and concepts, web developers can create effective and efficient HTML and CSS code for their projects, resulting in visually appealing and user-friendly web pages.