The main function of a proxy server in network security is to act as an intermediary between a user’s device and the internet. Proxy servers provide several key benefits, including anonymity by masking the user's IP address, content filtering to block access to certain websites, and security by preventing direct exposure to potential threats online. By routing user requests through the proxy, it can also cache data to improve load times and conserve bandwidth, making it an essential component of an organization’s network security strategy.