This is a repackaged open source software product wherein additional charges apply for support. Varnish is a powerful HTTP accelerator and reverse proxy server that plays a crucial role in optimizing the performance of websites and web applications. It operates by storing frequently accessed content, such as images or entire web pages, in memory. When a user requests this content, Varnish can quickly serve it directly from memory, eliminating the need to regenerate the content from the web server.