What is the primary function of media queries in CSS?

The primary function of media queries in CSS is to create responsive designs for different screen sizes. Media queries allow developers to apply different styles based on the characteristics of the device being used, such as its width, height, orientation, and resolution. This flexibility is essential in modern web development, enabling websites to provide an optimal viewing experience across a wide range of devices, from mobile phones to tablets to desktop computers.

By using media queries, you can specify certain styles that only apply when certain conditions are met, such as when the viewport width is below a specific threshold. This means you can design a single website that adapts its layout and functionality depending on the user's device, improving usability and accessibility.

While changing color schemes can be achieved through CSS, it does not capture the full breadth of what media queries can do. They are not primarily used to define default styles for all elements or to combine multiple CSS files; their focus is squarely on adjusting styles based on device characteristics. This adaptability is why media queries are a cornerstone of responsive web design.