Cascading Style Sheets are the files responsible for the presentation of a website. All rules that affect the visual formatting are stored in these files. This lets the developer keep style information in a separate place from the content.
This separation strategy has a few benefits:
- Stylesheets may be cached, improving page load times
- May prevent the person in charge of updates from accidentally disturbing the design
- Stylesheets may be made interchangeable, allowing the webmaster to change the appearance of a website while not affecting content.