CSS is stands for Cascading Style Sheets,
CSS describes how HTML elements are to be displayed on screen,
CSS saves a lot of work. It can control the layout of multiple web pages all at once,
External stylesheets are stored in CSS files.
CSS was first proposed by Hakon Wium Lie on October 10, 1994. At the time, Mr. Lie was working with Tim Berners-Lee (father of Html) at CERN (The European Organization for Nuclear Research is known as CERN). Hakon Wium lie is known as father of CSS.
CSS was proposed in 1994 as a web styling language, to solve some of the problems of Html. There were other styling languages proposed at this time, such as Style Sheets for Html and JSSS but CSS won.
CSS level 2 specification was developed by the W3C and published as a recommendation in May 1998. CSS 2 includes a number of new capabilities like below;
CSS3 was started in 1998 but it has never been completed. Some parts are still being developed and some components work on some browsers. It published in June 1999. CSS 3 is divided into several separate documents called "modules". Each module adds new capabilities or extends features defined in CSS 2.
The biggest advantage of CSS is that it allows separating content of an html document from the style and layout of that document. It can thus make documents much easier to maintain and give much better control over the layout of your web pages, because content of an entire set of HTML pages can be easily controlled using one or more style sheets.
CSS Save lots of time - CSS gives lots of flexibility to set the properties of an element. You can write CSS once; and then the same code can be applied to the groups of HTML elements, and can also be reused in multiple HTML pages.
Easy maintenance - CSS provide an easy means to update document formatting and maintain consistency across multiple documents. By making one change to the website's CSS, elements in all the web pages will be updated automatically.
Pages load faster - CSS enable multiple pages to share formatting, and reduce complexity and repetition in the structural content. It significantly reduces the file transfer size, which results in a faster page loading.
Superior styles to HTML - CSS has much wider presentation capabilities than HTML, so you can give far better look to your HTML pages in comparison to the HTML presentational elements and attributes.
Multiple Device Compatibility - CSS can also allow the HTML document to be optimized for more than one type of device or media. Using CSS the same HTML document can be presented in different viewing styles for different rendering devices such as computer screen, cell phones, printer, etc.