VPN - virtual private network
VPN is pronounced as separate letters and is short for virtual private network.
VPN is a network that is constructed by using public wires — usually the Internet — to connect to a private network, such as a company's internal network. There are a number of systems that enable you to create networks using the Internet as the medium for transporting data. These systems use encryption and other security mechanisms to ensure that only authorized users can access the network and that the data cannot be intercepted.
Consumer VPN Services
Consumers use a private VPN service, also known as a VPN tunnel, to protect their online activity and identity. By using an anonymous VPN service, a user's Internet traffic and data remain encrypted, which prevents eavesdroppers from sniffing Internet activity. A VPN service is especially useful when accessing public Wi-Fi hotspots because the public wireless services might not be secure. In addition to public Wi-Fi security, a private VPN service also provides consumers with uncensored Internet access and can help prevent data theft and unblock websites.
Corporate VPN Communications
Companies and organizations will use a VPN to communicate confidentially over a public network and to send voice, video or data. It is also an excellent option for remote workers and organizations with global offices and partners to share data in a private manner.
One of the most common types of VPNs used by businesses is called a virtual private dial-up network (VPDN). A VPDN is a user-to-LAN connection, where remote users need to connect to the company LAN. Another type of VPN is commonly called a site-to-site VPN. Here the company would invest in dedicated hardware to connect multiple sites to their LAN though a public network, usually the Internet.
Recommended Reading: What Makes a Virtual Private Network Private?