HTTP Cache is a mechanism that stores copies of web resources, like images and HTML pages, to improve loading times and reduce server load. When a user visits a website, the browser checks if it has a cached version of the resource. If available, it retrieves the cached version instead of downloading it again from the server. Caching can significantly enhance user experience by speeding up page loads and minimizing data usage. It works based on specific rules set by the server, such as expiration times and validation checks, ensuring that users receive up-to-date content when necessary.