A virtual private network, usually just called a VPN, is an extension of a private network outside of the physical hardware that comprises that private network. The connection is considered virtual because it uses a combination of software controls and tunneling to create the connection, instead of using hardware such as dedicated lines. Virtual private networks are commonly used in the business world to either allow employees and other authorized personnel to establish a connection to the company's servers from a remote location, or to connect two of the company's separate, private networks into one wide area network (WAN). Once connected through a VPN, employees or branch offices get an internal IP address, and have access to anything that they could normally access if they were physically plugged in to the private network.

On top of allowing for remote connections, VPNs are also popular because of the security they provide. Commonly, the VPN software will encrypt the data packet so that it is unintelligible to anyone who might be snooping on the public network. Additionally, VPNs use a process called "tunneling," which encapsulates the encrypted data packet within another packet, adding another layer of security and making it extremely difficult for prying eyes to see the payload. It's for this reason that some people choose to use a personal VPN (set up between themselves and a proxy server) to either get around content filters or to secure themselves when using a public Internet connection. As VPNs grow in popularity, setting one up is becoming easier. Businesses normally use a dedicated network access server to set up strong authentication controls, but anyone can set up a virtual private network between two devices using a VPN built into the latest versions of Windows.