original: An open proxy is a proxy server that is accessible by any Internet user.
simplifications: An open proxy is a proxy server that available for any Internet user. An open proxy server can be opened by any internet user. An open proxy is a server that any Internet user can use. An open proxy is a cloaked computer that can be accessed by web users. An open proxy is a proxy server that any Internet user can access. An open proxy is a proxy server any Internet user can access. An open proxy is a server that is accessible by an Internet user. An open proxy is a middle-man server that can be accessed by anyone. A proxy server accessible by any Internet user is called an open proxy. An open proxy is a proxy server that can be reached by any Internet user.