
CSS is the short form of Cascading Style Sheets. In the year 1996, the World Wide Web Consortium introduced it with the purpose of separating presentation (layout, fonts, page structure, colors etc) from the web page content (images, multimedia, written copy). Apart from this, another important goal of CSS is to increase web accessibility. In the true sense, CSS is an important tool for modern web designing.
Since CSS is being contained in a separate file from an HTML web page, it is often called the external style sheets. The CSS file usually tells the HTML page about how to style the the content of a website. In earlier times, HTML along with tables were used to construct web pages. However, with the technological advancement, the process has become more advanced and dynamic. In this era, a new concept is followed for designing web pages. This approach is known as CSS tableless design.
This tableless design is not possible without CSS. However, in the place of tables, a tableless designer can use “DIV”s (the short form of “division”). A DIV is basically a container, where web content is stored.

Reasons Behind Why Web Advances Uses CSS Tableless Design Website Development
Still now, there is a confusion regarding the superiority of CSS tableless design over the traditional table-based website design. However, some of the reasons for which CSS website design is more preferred for modern website designing are mentioned below:
Though tableless formats are being widely used for page layout control, it does not necessarily mean that tables are not being used anymore. They are merely not optimal for presentation purposes.