CSS describes how elements should be rendered on screen, in print, or in other media. Here are some key concepts and features of CSS:


Selectors are patterns that match one or more elements in an HTML document. CSS rules are applied to these elements based on their selectors.


Properties are the styling attributes applied to the selected elements. They define how the selected elements should appear.


Values are assigned to properties and determine how the property should be applied. For example, the color property can have values like names (e.g., "blue") or specific color codes (e.g., "#0066cc").

Selectors and Properties Cascade

CSS rules can be applied from different sources, such as user styles, author styles, and browser defaults. The cascade defines the order of priority when conflicting styles are encountered.

Box Model

The box model is a fundamental concept in CSS, defining how elements are structured in terms of content, padding, border, and margin.


CSS provides tools for controlling the layout of a web page. This includes properties like display, position, float, flexbox, and grid for creating responsive and dynamic layouts.

Responsive Design

CSS is crucial for creating responsive designs that adapt to different screen sizes and devices. Media queries are used to apply styles based on factors like screen width, height, or device characteristics.

Transitions and Animation

CSS allows for the creation of smooth transitions and animations. Properties like transition and keyframes are used to define the animation behavior.

Flexbox and Grid

CSS offers layout systems like Flexbox and Grid for creating complex and responsive layouts with ease.

CSS Preprocessor

Preprocessors like Sass or Less extend the functionality of CSS by introducing variables, nesting, and functions, making it more maintainable and modular.