What is the main purpose of a viewport in responsive web design?

The main purpose of a viewport in responsive web design is to adjust for different screen sizes for proper scaling. The viewport acts as a frame that determines how a web page is displayed on various devices, from desktops to smartphones. By specifying the viewport settings in the code, designers can ensure that the content of the web page scales appropriately, displaying correctly and allowing for a better user experience on diverse screen resolutions.

Responsive web design relies heavily on flexible grids, layouts, and images, which are all informed by the viewport settings. This allows the website to adapt dynamically to different devices, ensuring that users can navigate easily and interact with the content without the need to manually zoom or scroll excessively. This adaptability is crucial as it helps in maintaining the usability and accessibility of the web page across different platforms.