A proxy site is a web page that fetches another page on your behalf and shows it to you. You type an address into a box, the proxy's server requests it, and the result comes back through the proxy, so the site you visited saw the proxy's address rather than yours. It is the lightest possible version of what a VPN does, it needs no software, and the differences are larger than they look.
What it covers, and what it leaves alone
A proxy site covers exactly one thing: the page you loaded inside it. Everything else on the device carries on as normal, so another browser tab, an email client, an app on your phone and the operating system's own connections all use your ordinary address. A VPN operates at the device level and covers all of them. If the reason you want this is a single page on a single occasion, the proxy is proportionate; if it is anything ongoing, it is not.
The three things a proxy site does not do
It does not encrypt your connection to the destination in any way the proxy itself cannot see, because the proxy is the party fetching the page. It does not survive complex pages: video players, logins, anything that loads content from several domains tends to break or silently bypass the proxy. And it does not hide anything from the proxy operator, who by design sees every page you asked for and anything you typed into it.
Who runs free proxy sites, and how they are paid
Running one costs bandwidth, so it is worth asking what pays for it. The visible answer is usually advertising injected into the pages you view. The less visible answers are logging and reselling traffic. Neither is universal and neither is disclosed on most of these sites, which is the whole difficulty: with a paid provider the business model is on the pricing page, and with a free proxy it is generally nowhere.
When to use one anyway
For reading a single page that a network has blocked, on a device you do not control, where nothing you type is sensitive. That is a real situation and a proxy is a reasonable tool for it. For anything involving an account, a payment, a download or a habit, the device-level tool is the right shape, and this site exists to say what those cost.
Questions people ask about proxy site
Is a proxy site the same as a VPN?
No. A proxy covers one page in one browser; a VPN covers the whole device. A proxy does not protect what you type from the proxy operator.
Are free proxy sites safe?
The operator sees everything you load through them and most disclose nothing about what they keep. Treat anything you type into one as visible to a stranger.
Why does the video not play through a proxy?
Video players load content from several domains and often bypass the proxy entirely, which is why a page can appear to work while the media does not.