A VPN is a secure encrypted tunnel between 2 points on a network. The network that it passes through cannot see what is in it. But information that goes in and out the other end is not encrypted and is exposed to whatever network that goes through.
It is commonly used to connect remote offices to a company private network, or remote users directly from their computers to a company network.
Some people try to use a VPN to do things that they are not allowed to do on a network (like a school or work network), but if network admin knows what they are doing, they would block any known common VPN's. They are also used to make your IP to appear to be from a different location than you really are, since the IP that would show up would be the public IP at the other end of the VPN connection.
A VPN (Virtual Private Network) is basically a tunnel through the internet to a remote system. At anywhere you connect you get an IP address which completes the circuit to the internet. That connection can be seen as a "pipeline" to the internet. With a VPN you create another "inside pipeline" or a pipe within a pipe that connects you to another computer system and the communications to that system are all encoded. That VPN system then becomes your "internet connection point" not the place you are actually located. This keeps your connection private and not readable from the physical point you started from as the controlling system is the actual "gateway" to the internet.
It is very important that you can trust the VPN admins and operators! They can indeed "see" you and can track your requests as all your traffic goes to them first. It generally is considered much safer than using any PUBLIC connection as many people can "see" your traffic on simple public connections.
You can even supply your own VPN and your computer at home or office becomes your "connection point" thus all your internet is seen as coming from your OWN ISP at your own home and not from some airport, library, McDonalds, etc. If you are in Europe and use a VPN to a home computer in the US your connection is seen as coming from the US not Europe, etc. No one can see the traffic you send from Europe to your computer as it is encoded and not readable. Once you hit your home computer your ISP is back as the "normal" connection. The pipe within the pipe (or tunnel as it is called) is working.
it puts your computer on someone elses network as though it were actually there. It uses encryption to ensure on one can steal your data
A VPN stands for virtual personification net. Basically if while on the internet your computer falls of the Personification net is what "catches you." Hope this helps!