Here's a pretty typical story. A five-person team at an online furniture shop wants to keep an eye on what three rivals charge for sofas, so somebody writes a Python script on a Friday afternoon and lets it run.
By Monday the office IP is banned from two of those sites. That's usually the week someone starts reading about proxies.
The short version is that a proxy is a middleman server. It sends requests for you, so the website sees its address and not yours. The long version is messier, because the proxies people actually pay for behave in very different ways.
Forward, Reverse and Everything in Between
Most of what that team will deal with are forward proxies. They act for whoever's sending the request, same as the office gateway that logs what staff browse at work. The website on the other end has no idea the gateway is even there.
Reverse proxies flip it around. They sit in front of a website and take the hits before the real server does, which is how a small store gets through a Black Friday rush without falling over.
Funny enough, the rival sites that blocked the script were almost certainly behind one. And it probably did the blocking, after spotting 400 requests a minute from one office address.
So when people compare different proxy servers, they're mostly comparing forward proxies, and the questions that matter are pretty specific. What protocol does it speak? Whose network does the IP belong to, and how often does it change?
Protocols, Briefly
HTTP proxies are the oldest kind, and they can read plain web traffic, headers and all. Squid, the open-source one that's been around since the mid-'90s, still defaults to port 3128 and still runs in a lot of offices. It caches pages too, which used to save real money back when bandwidth was expensive.
HTTPS made them a lot less nosy. The browser sends a CONNECT request, the proxy sets up an HTTP tunnel, and after that it just passes along encrypted data it can't open. It knows the domain, and that's roughly where its knowledge ends.
SOCKS5 is the other big one. It's laid out in RFC 1928, handles pretty much any TCP traffic plus UDP, and doesn't try to understand what it's carrying. Good for odd jobs, no help at all with caching.
The IP Is What Sites Actually Check
Back to the furniture team. Their first move is usually datacenter proxies, since they're cheap and quick to set up, but the IPs come from hosting companies like AWS or Hetzner and a site can spot that with one lookup.
Residential proxies get around that by borrowing real home connections. They cost more (normally per gigabyte) and they're slower, but the rival's site just sees another shopper looking at sofas.
ISP proxies mix the two: IPs registered to normal internet providers, running on datacenter servers. Mobile proxies use 4G and 5G carrier IPs, and since one carrier IP can be shared by hundreds of phones, blocking it means blocking real people too. Not surprisingly, mobile tends to be the priciest option on the list.
Rotation (and When Not to Use It)
Rotation just means the IP changes, either on every request or every few minutes. For checking 2,000 sofa listings every morning, that's ideal, since no single address shows up often enough to look suspicious.
But logins hate it. If the address changes in the middle of a session, most sites log you out, which is why sticky sessions hold one IP for 10 or 30 minutes.
For a team like this, rotating datacenter IPs would probably cover most of the work. Residential bandwidth starts making sense when the blocks keep coming back anyway. Mobile is a last resort for most teams, mostly because of the price.
What's Next
The sites on the other end keep getting smarter. Cloudflare runs one of the biggest reverse proxy networks around, and its bot checks now look at TLS fingerprints and browser behavior, not just the IP. A perfect residential address won't save a script that clicks through pages in exactly 0.5 seconds every time.
IPv6 adds another wrinkle, with about 340 undecillion addresses against IPv4's 4.3 billion. When addresses get that cheap, a fresh IP on its own stops meaning much, and knowing how each type of proxy actually behaves will count for more than whatever plan happens to be on sale.
