Virtual private network
A virtual private network or VPN for short, is a way of connecting a computer to a remote network. Most people using computers connect to the World Wide Web using a normal network - they use dial-up or broadband. A VPN is a little bit different. It's used by some workers to connect to work using a laptop - they can check their work email and see work websites which can not be seen on the normal internet.
Recently VPN is often used to access websites that are blocked in some countries, like China. Many people also use a VPN to protect their internet activity while using public WiFi. While VPN usage varies by country, you can see a full list of reasons why, where, and how often people use a VPN at GlobalWebIndex.