Explanation:
A proxy is a device that acts on behalf of other(s). A commonly used proxy in computer networks is a web proxy. Web proxy functionality is often combined into a proxy firewall.

A proxy firewall can be thought of as an intermediary between your network and any other network. Proxy firewalls are used to process requests from an outside network; the proxy firewall examines the data and makes rule-based decisions about whether the request should be forwarded or refused. The proxy intercepts all of the packets and reprocesses them for use internally. This process includes hiding IP addresses. The proxy firewall provides better security than packet filtering because of the increased intelligence that a proxy firewall offers. Requests from internal network users are routed through the proxy. The proxy, in turn, repackages the request and sends it along, thereby isolating the user from the external network. The proxy can also offer caching, should the same request be made again, and it can increase the efficiency of data delivery.