CSS (Cascading Style Sheets) is a style sheet language is used to add style, layout, and design to web pages and web applications.

CSS (Cascading Style Sheets) is a style sheet language used for describing the presentation of a document written in HTML (Hypertext Markup Language). CSS is used to add style, layout, and design to web pages and web applications.

The main benefits of using CSS include:

1. Separation of content and presentation: CSS allows web developers to separate the presentation and layout of a web page from the content of the page. This means that developers can create a consistent look and feel across an entire website without having to apply the same styling rules to each individual page.

2. Easy maintenance and updates: By using CSS to style web pages, developers can easily update and modify the appearance of a website without having to change the underlying HTML code. This makes it much easier to maintain and update large websites with multiple pages.

3. Faster page loading times: CSS allows web pages to load faster by reducing the amount of HTML code needed to style a page. By using external style sheets, the same styles can be applied to multiple pages, reducing the amount of code that needs to be downloaded and improving page loading times.

4. Better accessibility: By using CSS, web developers can create more accessible websites that are easier for users with disabilities to navigate. CSS allows developers to create a consistent and logical hierarchy of content that is easy for screen readers to understand and navigate.

5. Cross-browser compatibility: CSS is supported by all modern web browsers, making it a reliable way to add styling and layout to web pages that will work across different devices and platforms.

Overall, CSS is an essential tool for web developers who want to create attractive, user-friendly, and accessible web pages and web applications.