A computer and associated software which will pass on a request for a URL from a World-Wide Web browser such as Mosaic to an outside server and return the results. This provides clients that are sealed off from the Internet a trusted agent that can access the Internet on their behalf. Once the client is properly configured, its user should not be aware of the proxy gateway.

A proxy gateway often runs on a firewall machine. Its main purpose is to act as a barrier to the threat of crackers. It may also be used to hide the IP addresses of the computers inside the firewall from the Internet if they do not use official registered network numbers.

Browsers such as Mosaic and Netscape can be configured to use a different proxy or no proxy for each URL access method (or "scheme") - FTP, Gopher, WAIS, news, and HTTP.

Mosaic and proxy gateways.

Compare proxy server.