Conditional requests

**Conditional requests**

Conditional requests are a feature in HTTP that allow clients to make requests to a server based on certain conditions, such as whether a resource has been modified since the last time it was accessed. This technique helps optimize web performance by reducing unnecessary data transfer and improving caching efficiency. Common conditional request headers include `If-Modified-Since` and `If-None-Match`, which work with server responses like `304 Not Modified` to indicate that the cached version of a resource is still valid. Understanding conditional requests is essential for developers looking to implement effective caching strategies and improve the speed and responsiveness of their websites or applications.