Public networks are inclusive and anyone with the proper resources should be able to connect to them. This means that the average person can access a public network from many locations using simple hardware and software. Examples of public networks are the Internet and the worldwide telephone system. Private networks are exclusive and connectivity is limited to a select group of people. This means that a person must have the correct hardware, software, affiliation and location to access a private network.
Many large corporations own private networks that span the globe.
With these definitions in hand, a virtual private network can be defined as the bridge between a private network and a public network. Consider a scenario where your boss has allowed you to work from home. At home you have access to the public network called the Internet. To work effectively at home, you want to access the private network at your company to share files and manage e-mail. Using VPN software or hardware, you could log in to your company's private network from your public Internet connection at home.