The purpose of a caching mechanism in web applications is to improve performance and reduce latency by temporarily storing frequently accessed data. By keeping copies of static resources, such as images, scripts, and HTML pages, closer to the user or in the browser, caching minimizes the need for repeated server requests. This leads to faster load times and a smoother user experience. Caching can be implemented at multiple levels, including browser caching, server-side caching, and content delivery networks (CDNs). Ultimately, effective caching strategies enhance overall application efficiency and reduce server load during peak traffic periods.