A caching mechanism in web applications serves to temporarily store frequently accessed data to reduce latency and improve load times. By saving copies of web pages, database queries, or API responses, caching allows users to retrieve information faster without needing to re-fetch it from the original source. This mechanism not only enhances user experience by providing quicker access to information, but it also reduces server load and bandwidth consumption. Overall, caching is essential for optimizing web performance and ensuring efficient resource utilization.