What is PAC?

PAC (Proxy Auto-Config) is a file format that defines how web browsers and other user agents automatically choose an appropriate proxy server (access point) for fetching a given URL. It contains a JavaScript function, 'FindProxyForURL(url, host)', that determines whether to use a proxy, and if so, which proxy to use. PAC files are often used in corporate networks to manage internet access and load balance requests across multiple proxy servers. They enhance security by filtering web content.