Stands for "Virtual Private Network" (not a successor to the UPN television network). VPN is a network term that most computer users don't need to know, but at least you can impress your friends by talking about it. A virtual private network is "tunneled" through a wide area network WAN such as the Internet. This means the network does not have to be located in one physical location like a LAN. However, by using encryption and other security measures, a VPN can scramble all the data sent through the wide area network, so the network is "virtually" private.
Businesses often use VPNs to communicate across multiple locations. For example, a large company that has offices in several cities may need to send data to the different locations via the Internet. To keep the information secure, the company might set up a VPN with an encrypted connection. This is similar to having a secure intranet over the Internet. On a smaller scale, individual users may have a VPN account with their company, which allows them to connect to their office computer from their home or another location. This is especially helpful for business travelers who need to access office data from their laptops.