'CSS (Cascading Style Sheets)' is a crucial language in web development, used for styling HTML or XML documents. It empowers developers to style webpages, managing aspects like layout, colors, fonts, and more. CSS distinguishes between content (HTML) and style (CSS), leading to neater code structures and simplified maintenance.

The inception of CSS can be traced back to 1994, thanks to Håkon Wium Lie, coinciding with the rising popularity of HTML. CSS's emergence marked a transformative era in web design, enabling the distinct handling of web content and its stylistic elements. This differentiation greatly simplified the process of building and managing intricate websites, reducing the need for repetitive HTML styling alterations.

CSS empowers developers to define stylistic rules for web elements, facilitating a uniform appearance across multiple pages of a website. It's pivotal in crafting responsive designs, ensuring websites adjust seamlessly to various devices, from large desktop screens to compact mobile displays.

Since its introduction, CSS has undergone significant evolution, with CSS3 being the latest major update. CSS3 brought forward advanced features such as animations, transitions, gradients, and grid systems, elevating the potential for creating more dynamic and visually engaging webpages. The advent of CSS3 modules has enabled more sophisticated styling approaches, shaping the contemporary web experience.

To sum up, CSS is an essential asset for web developers and designers. It not only adds a creative and aesthetic dimension to web applications but also is key in shaping user interface design, enhancing accessibility, and improving overall usability. In concert with HTML and JavaScript, CSS forms the foundational trio of technologies underpinning the World Wide Web.