A HTTP proxy server sits between your HTTP requests in order to securing and provide anonymity on internet.
When using a proxy ip to connect to a proxy server, website you visit you will visit through the proxy server.
A request is sent to the proxy server, the proxy server is connecting to the website you visit, is gathering information from that website,
and it will return the information to you. In this way, the website you are visiting will see that the request is coming from the proxy server,
and not from you, thereby your ip will not be disclosed, an you can browse safe and secure.