VPN is an abbreviation for Virtual Private Network. Private network is a network for select users that has a firewall enabled to prevent intrusion from the Internet. Even though such networks tend to be safe from intrusion, it causes a problem for users. It becomes difficult to get past the firewall, if someone wants to access email or their own files. Therefore, a specific kind of software or electronic hardware is used. This is called a VPN or virtual private network that can help users access their email or files from private networks, without difficulty. VPN is a private communications network. It is usually used within a company, or by many different companies or organizations, communicating over a public network. VPN message traffic is carried on a public networking infrastructure (Internet) using standard protocols.

VPN clients are used in three scenarios. It is used to support remote access to an intranet. It is used to support connections between multiple intranets within the same organization. It is also used to join the networks between two organizations, forming an extranet. Experts in VPN technology warn against connecting the client computer to the Internet directly. Connecting the computer directly when there is only one Internet connection bypasses the firewall. This destroys the security and access-sharing capabilities that the firewall provides. Spreading the firewall to accommodate the VPN traffic will help retain the fire walling security provided by it. It will also permit the other systems on the local network to access the Internet. The Internet can be accessed even if the VPN networks connection is not active.

If a firewall is used in an environment of many thousand users, it is considered safer to make the VPN client users to go through that firewall. This is done for security reasons. This approach is better than providing the clients with modems. Clients having modems can dial out on their own when they need to use the VPN and this will totally defeat the purpose of a firewall.