"Progressive enhancement" is an approach in web development that involves designing and building web pages in a way that allows for a graceful degradation of functionality for users who may be using older browsers or devices with limited capabilities, while providing advanced functionality for users with modern browsers and devices.
This approach allows web developers to create websites that are flexible and adaptable to different user needs and environments, and can be accessed by as many people as possible. It also ensures that the website remains functional even when certain features or technologies are unavailable, such as when a user is using an older browser or has limited internet connectivity.
When answering this question in an interview, it's important to provide a clear and concise explanation of the concept, and to provide examples of how it can be implemented in web development. You can also mention the benefits of using this approach, such as improved accessibility, better performance, and increased flexibility.