Alongside HTML and JavaScript, it is a primary language which is used to create websites or web based content.
CSS includes the instructions on how to present the content, such as the layout, colours and fonts, controlling almost every visual aspect of a website. When using CSS to create the visual layout, it can be included directly into an HTML file, to determine the style, design and layout of the page.
However, rather than being embedded directly within HTML web page, in most cases, it is linked to a separate CSS file. This reduces complexity and repetition across a website, while improving accessibility and page load times among the pages that share the same CSS file, especially when cache functions are enabled.
With the introduction of smartphones and tablet devices, CSS allows for the use of multiple layouts and design elements. Referred to as 'Responsive Design', it uses CSS, in combination with HTML code, to create website layouts which respond to the different screen sizes across various devices.
