A Virtual Private Network is a way to establish a secure "private network" to a computer at another location through the public Internet. VPNs are frequently used by businesses to connect their offices and allow employees to telecommute and establish a connection to their company network. Simply, when you are not in your office, all you need to do is dial up to Internet and connect to your company network, which enables you to use all resources as if you were at your desk.

In a sense, VPNs are similar to wide area networks (WAN) or a securely encrypted tunnel, but the key feature of VPNs is that they are able to use public networks like the Internet rather than rely on expensive, private leased lines. At they same time, VPNs have the same security and encryption features as a private network, while taking the advantage of the economies of scale and remote accessibility of large public networks.

VPN is an especially effective means of exchanging critical information for employees working remotely in branch offices, at home, or on the road. It can securely deliver information between vendors, suppliers, and business partners, who may have a huge physical distance between them. Since companies no longer have to invest in the actual infrastructure themselves, they can reduce their operational costs by outsourcing network services to service providers. VPNs can also reduce costs by eliminating the need for long-distance telephone charges to obtain remote access, as client need only call into the service provider's nearest access point.