What term describes using HTML and CSS to automatically adapt a website's layout to different devices?

The term that describes using HTML and CSS to automatically adapt a website's layout to different devices is known as Responsive Web Design. This approach utilizes fluid grids, flexible images, and media queries to ensure that the content is displayed optimally across a wide range of devices, from mobile phones to desktop computers.

Responsive Web Design allows designers to create a single website that provides a seamless user experience regardless of the screen size or resolution. It emphasizes the importance of proportional scaling and adapting the layout based on the viewer's device, thereby improving usability and accessibility. This methodology has become essential in modern web development as it addresses the diverse ways users access websites.

In contrast, the other terms do not capture the principle of flexible layouts and adaptability inherent in Responsive Web Design. The terms Auto Adjust and Dynamic Web Design, while they may suggest some form of adjustment, do not specifically define the systematic approach provided by Responsive Web Design, which is characterized by its reliance on CSS techniques and a focus on providing a consistent experience across various devices. Hypertext Markup Language refers specifically to the markup language used to create web pages, not to the adaptive design methodology itself.