The majority of typical VPN-related documents define VPN, as the extension of a private network. However this type of definition means nothing and only characterises the VPN concept as a determining factor of a private network, which is still somewhat unclear. VPN is an abbreviation for Virtual Private Network.
When I started using the Internet during my University days, an intelligent friend of mine told me that SSH is a client application needed to build up a secure connection with the University’s server. I took his word for it, but later my curiosity prompted me to ask a question “Why?”