A private network infrastructure is exclusively maintained for the communication needs within an organization, generally isolated from public access to secure sensitive data and operations. An intranet used by company employees is a prime example of such a network. Public networks are designed for public access, thus unfit for internal, sensitive communications. A VPN, although it uses public networks, essentially creates a 'private tunnel' and is mainly used for secure connections over the internet. Metropolitan area networks (MAN) typically span larger geographic areas like cities and involve multiple public or private users, making them broader than just an organization's private network.