What is a proxy?

Reading your message reminds me a bit of my class! xD

In fact, the origin of the proxy dates back to the time when connections were not great... I'm talking about 56K dial-up lines or even ISDN. In a business setting or any other location where several people gather, you might have individuals frequently visiting the same pages. The problem is that, as mentioned earlier, connection speed leaves something to be desired and we can't always serve everyone efficiently. So instead of systematically wasting time, we set up a proxy server that checks if it already has the requested page in cache; if so, it sends that page back to the requester, otherwise, it allows the request to go further. When the HTTP server responds, we update the cache: the site will now be available for other requests.
And the proxy remains with us despite high-speed connections. It is often used to hide one's IP or bypass restrictions, as in countries where the government doesn't grant freedoms to internet users.

I'm not sure that this is its only use nowadays.
Even with a T3 connection, can you imagine the load of a very large company?
Maybe we keep all the usefulness of a proxy but now on larger volumes.
In any case, using a proxy to "throw off the scent" is common.