CSS is a formal language used to describe the appearance of a document created using a markup language (HTML, XHTML, XML). The name comes from Cascading Style Sheets, which means “cascading style sheets.
The purpose of CSS is to separate what sets the appearance of a page from its content. If the document is created using HTML only, it defines not only each element, but also how it will be displayed (color, font, block position, etc.). If, however, cascading style sheets are connected, HTML only describes the sequence of objects. CSS is responsible for all their properties. In HTML, it is enough to write the class without having to list all the styles every time.
This technology:
- provides relatively simple and fast development, because once created, the design can be applied to many pages;
- increases flexibility and ease of editing – it is enough to make changes in CSS, so that the design has changed everywhere;
- makes the code more simple, reducing the repetition of elements. It is easier to read the programmers and search bots;
- speeds up load time, because CSS can be cached the first time it is opened, and only the structure and data are read in subsequent openings;
- increases the number of visual solutions for displaying content;
- provides the ability to easily apply different styles to the same document (for example, create an adapted version for mobile devices, or special styles for the visually impaired).
- That is, cascading tables are not only for the embodiment of design, but also fundamentally change the approach to site building, simplifying the work of developers and providing flexibility. This is what CSS is for.
The need for CSS was recognized by the W3C consortium in the 1990s. In 1996, the standard was adopted CSS1, which allows you to change the font, color, text attributes, alignment and indentation. In 1998 came the release of CSS2, which added the ability to use block layout, sound tables, generated content, pointers, page media. CSS3 version noticeably increased the possibilities of styles: it became possible to create animated elements without using JavaScript, support for anti-aliasing, shadows, gradients, etc. appeared. The specification was divided into modules, each of which began to develop separately. Since 2011, the development of CSS4 modules is underway.