Explain the difference between adaptive and responsive design.

Adaptive design and responsive design are two approaches used in web design to create websites that adapt to different devices and screen sizes, but they differ in their implementation and approach:

1. **Responsive Design**:
   - Responsive design uses fluid grids, flexible layouts, and CSS media queries to create a single website that adjusts dynamically to different viewport sizes and resolutions.
   - With responsive design, the layout and content of the website respond fluidly to changes in screen size, allowing for a seamless user experience across devices.
   - Responsive design typically relies on a combination of percentage-based widths, flexible images, and breakpoints to reflow and rearrange content based on the available screen space.
   - Responsive design offers a more flexible and fluid approach to creating adaptive layouts, allowing for a more consistent and unified user experience across devices.

2. **Adaptive Design**:
   - Adaptive design involves creating multiple fixed-layout versions of a website, each optimized for specific device categories or screen sizes.
   - With adaptive design, the website detects the user's device or viewport size and serves a predefined layout optimized for that particular device or screen resolution.
   - Adaptive design typically involves creating separate layouts or templates for different device categories (e.g., smartphones, tablets, desktops) and using server-side detection or client-side scripting to determine which layout to serve.
   - Adaptive design offers more control over the user experience on different devices, allowing designers to tailor the layout and content for specific screen sizes and device capabilities.

In summary, the main difference between adaptive and responsive design lies in their approach to creating adaptive layouts. Responsive design uses fluid layouts and CSS media queries to create a single flexible layout that adjusts to different screen sizes dynamically, while adaptive design involves creating multiple fixed-layout versions of a website optimized for specific device categories or screen sizes. Both approaches have their advantages and trade-offs, and the choice between them depends on factors such as design requirements, project scope, and target audience.