Glossary · Networking
Forward proxy
A proxy that sits in front of the client and forwards its outbound requests, the ordinary sense of the word proxy, as opposed to a reverse proxy that fronts a server.
A forward proxy acts on behalf of the person making a request. Your traffic goes to the proxy, the proxy makes the request to the destination on your behalf, and the reply comes back the same way, so the destination sees the proxy's address instead of yours. Every residential, datacenter, ISP and mobile proxy used for browsing or scraping is a forward proxy in this sense.
The contrast with a reverse proxy is about which side is being represented. A forward proxy represents the client and is chosen by the client; a reverse proxy represents the server and is chosen by the site operator, usually for caching, load balancing or defence. The machinery looks similar, but they point in opposite directions.
Knowing which one you are dealing with settles a lot of confusion. If you are configuring an address and port in your own client to change how you appear to a site, you are using a forward proxy. If a site's own infrastructure is deciding whether to serve or challenge you, a reverse proxy is part of what is doing the deciding.
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