>>12793826With proxies if for example you want to post "hi" on 4chan you tell a proxy server "post hi on 4chan" and he does that for you, they're a trivial tool that is pretty much deprecated at this point
VPNs are more complex and can actually work in different ways but what happens basically is that you send the post by yourself instead of asking a server to do that for you, you camouflage your IP by "pretending" to join a LAN
