A virtual private network (VPN) is a computer network that allows companies/users to remotely access private data over public networks securely. A VPN provides a cost-effective alternative way of allowing remote users and offices flexible access to crucial data necessary to conduct business on a daily basis.  It also allows companies/users to expand the reach of their networks without heavily investing in expensive infrastructure expansion. 

VPN’s use tunneling protocols that encrypt data at the sending end of the network tunnel and then decrypt the data the receiving end of the tunnel.  There are two types of common VPN’s , Client-to-Lan/Remote access VPN and Site-to-Site VPN. 

A video explantion of the the various VPN's and VPN solutions can be seen here.

Video credit to www.howstuffworks.com