SOCKS is a de facto standard for circuit-level gateways.
Another use of SOCKS is as a circumvention tool, allowing traffic to bypass Internet filtering to access content otherwise blocked, e.g., by governments, workplaces, schools, and country-specific web services.
Some SSH suites, such as OpenSSH, support dynamic port forwarding that allows the user to create a local SOCKS proxy. This can free the user from the limitations of connecting only to a predefined remote port and server.
The Tor onion proxy software presents a SOCKS interface to its clients.