What is meant by 'responsive design' in the context of a User Interface?

Responsive design refers to the approach in web and user interface design that ensures content is displayed optimally across a range of devices and screen sizes. This concept is essential in today's digital landscape, where users access websites and applications from desktop computers, tablets, and smartphones, each with different screen dimensions and resolutions.

A responsive design employs fluid grids, flexible images, and CSS media queries to adapt layouts to the user's device. For instance, it might adjust the number of columns displayed, resize images, or change the navigation structure based on the available screen space. This approach improves usability and accessibility, enhancing the overall user experience regardless of the device.

In contrast, designs that involve complicated elements, ignore mobile users, or remain static are not suited for a variety of devices and can lead to a poor user experience, diminished accessibility, and a lack of engagement by the audience. Hence, responsive design is fundamental in creating adaptable, user-friendly interfaces in modern web development.