Squid is proxy server software released by Duane Wessels in 1998 as the last pre-commercial version of the Harvest object cache, naming it to differentiate it from the main NetCache branch, the development of which has not been continued. Squid is licensed under a GNU General Public License and supports, among others, the HTTP, HTTP / 2, HTTPS and FTP protocols..
Squid servers run on common operating systems, such as various Linux distributions or Mac OS X and Windows systems , either with the device's own command tool or through a graphical interface such as GAdmin-SQUID or SquidMan.
Squid is used as a proxy-cache by thousands of web administrators. Wikipedia, without going any further, used several Squid proxy servers for years to deliver the content, with the aim of decongesting the database and the web server. Also, the fact of supporting the HTTPS protocol makes it ideal for establishing secure SSL connections. In another area, Internet providers also use it as a transparent proxy in order to optimize Internet access. Of course, it can also be used as a forward proxy for a single client, so that the IP address itself is hidden, thus providing additional protection in addition to the packet filtering of the firewall. The SquidGuard extension allows you to filter packets autonomously..