What is a proxy server and how does it work?

A proxy server is a computer that makes web requests on your behalf. Instead of your machine talking to a website directly, it talks to the proxy, the proxy talks to the website, and the answer comes back the same way. The website sees the proxy's IP address, not yours.

That is the entire idea. Everything else you have read about proxies, all the types and protocols and pricing tiers, is just variations on that one trick.

What actually happens to your request

Say your scraper wants to load a product page. Without a proxy, the request leaves your machine, hits the site, and the site logs your IP. With a proxy configured, the journey changes:

1. Your software sends the request to the proxy's address and port.
2. If the proxy requires it, your software authenticates with a username and password.
3. The proxy opens its own connection to the website and forwards your request.
4. The website answers the proxy, and the proxy relays the response back to you.

From the website's point of view, the visitor is the proxy. If you switch proxies between requests, the site sees a different visitor each time. That is why proxies are the backbone of web scraping: they let one machine look like many.

Forward and reverse proxies

What I described above is a forward proxy: it sits in front of you and hides the client. You will also hear about reverse proxies, which sit in front of websites and hide the servers. Cloudflare and nginx are the famous examples. Same word, opposite job. When people talk about buying proxies for scraping or privacy, they always mean forward proxies, and that is what the rest of this guide covers.

What people actually use proxies for

Web scraping is the big one. Sites throttle or block IPs that make too many requests, so scrapers spread their traffic across a pool of proxy addresses to stay under the limits.

Geo testing comes second. If you need to see your ads, prices, or search results as a user in Tokyo or Toronto would, a proxy in that country is the cheapest way to look.

Account management is common too. People running several accounts on one platform give each account its own proxy so the accounts do not obviously share an address.

And then there is basic IP privacy: hiding your home address from a site, or reaching one that blocked your network. A proxy does that job, with limits we cover below.

The three axes of proxy types

Proxy shopping gets confusing because sellers mix three unrelated categories into one product name. Untangle them and everything makes sense:

• Protocol: HTTP or SOCKS. This is the language your software uses to talk to the proxy. HTTP proxies understand web traffic. SOCKS proxies relay any traffic without inspecting it. Our SOCKS5 vs HTTP guide picks this apart properly.
• Address family: IPv4 or IPv6. The kind of IP address the proxy uses. IPv4 works everywhere and costs more. IPv6 is nearly free and only works on sites that support it. Details in IPv4 vs IPv6 proxies.
• Source: datacenter, residential, or mobile. Where the IP comes from. Datacenter IPs are cheap and easy to detect. Residential IPs belong to real home connections and blend in. Mobile IPs come from carrier networks and are the hardest to block. The tradeoffs live in residential vs datacenter proxies.

So a "residential SOCKS5 IPv4 proxy" is not some exotic species. It is one choice from each column.

What a proxy does not do

A proxy changes your visible IP address. It does not encrypt anything. If your traffic is HTTPS (most of the web), it was already encrypted and stays that way. If it is plain HTTP, the proxy operator can read it, which is one good reason to be picky about free proxies from random lists.

A proxy also does not make you anonymous in any deep sense. Websites have more signals than your IP: browser fingerprints, cookies, account logins, behavior patterns. A proxy swaps one signal out of many. For the difference between this and a real encrypted tunnel, read proxy vs VPN.

How to tell if a proxy works

You test it. Paste the address into our free proxy checker and you will see in a few seconds whether it connects, which IP it exits from, what country that IP sits in, and how long the round trip took. If you prefer the command line or want to test from your own machine, how to test if a proxy is working walks through three methods.

One habit worth building: test proxies before you build on them, not after something breaks. A dead proxy discovered by your error logs at 2am is a much worse experience than one discovered by a ten-second check.