VPN stands for "virtual private network." It is basically a way to securely transmit private data over a public network (e.g., the Internet) using encryption and other security mechanisms.
There are various types of VPNs. For mobile workers, VPNs typically mean "remote access VPNs," where a remote worker connects to a corporate office over a secure VPN tunnel in order to exchange data and share resources, just as if he/she was on the internal network.
Other types of VPNs include site-to-site VPNs, where one entire local area network (LAN) is joined or connected to another LAN.
Often used interchangeably with: "remote access
VPN implementations can be software-based, as with Cisco's VPN client and server software, or a combination of hardware and software, such as Juniper Network's routers that are compatible with their Netscreen-Remote VPN client software.
Another form of VPN is SSL (Secure Sockets Layer) VPN, which allows the remote user to connect using just a Web browser, avoiding the need to install specialized client software. There are pros and cons to both traditional VPNs (typically based on IPSec protocols) and SSL VPNs.
