What does 'responsive design' refer to in web development?

The concept of 'responsive design' in web development primarily focuses on creating web pages that automatically adjust and provide an optimal viewing experience across a wide range of devices and screen sizes. This approach ensures that a website is user-friendly on various platforms, such as desktops, tablets, and smartphones, by utilizing flexible grids, layouts, images, and CSS media queries.

Responsive design aims to eliminate the need for different versions of a website for different devices, allowing for a single, adaptable webpage that rearranges its content based on the screen dimensions and resolution. This not only enhances the user experience but also can lead to improved search engine rankings since search engines favor mobile-friendly websites.

The other options refer to different web development concepts: improving loading speed is essential but separate from the purpose of responsive design; designing solely for mobile devices neglects the broader principle of adaptability; and strategies for maximizing SEO performance involve a variety of practices beyond just responsive design.