The previous answers were accurate, but perhaps too terse. I will try to add some examples.

First of all, the word "proxy" describes someone or something acting on behalf of someone else.

In the computer realm, we are talking about one server acting on the behalf of another computer.

For the purposes of accessibility, I will limit my discussion to web proxies - however, the idea of a proxy is not limited to websites.

FORWARD proxy

Most discussion of web proxies refers to the type of proxy known as a "forward proxy."

The proxy event, in this case, is that the "forward proxy" retrieves data from another web site on behalf of the original requestee.

A tale of 3 computers (part I)

For an example, I will list three computers connected to the internet.

• X = your computer, or "client" computer on the internet
• Y = the proxy web site, proxy.example.org
• Z = the web site you want to visit,

Normally, one would connect directly from X --> Z.

However, in some scenarios, it is better for Y --> Z on behalf of X, which chains as follows: X --> Y --> Z.