Cascading Style Sheets (CSS) is a style sheet language that helps website content and design settings (e.g. colors and layout) to be defined separately. The HTML and XML documents only contain information on the content, the internal structure, or individual website components, while the design elements are listed separately in CSS files. If style sheets are used, the web server has to pass these onto the browser each time a site is called up. This is all done in addition to the HTML document and the implemented multimedia content (images, videos, etc.), which has an effect on the loading time. The more complex and larger the CSS files are, the longer the visitor has to wait until the site has completely finished loading. By compressing the CSS, you can reduce the size of the CSS file and increase the performance of your website.