VPN, which is a private network that uses the Internet to connect to remote sites and users, allows "virtual" connections from the remote site or user to be routed through the Internet to the company's private network. This is an alternative method to using a dedicated, real-world connection to an office network or LAN.
Since the Internet is a public domain, anyone with a computer, a modem, a phone line and Internet service can access it. Though the Internet fosters the idea of global community, VPN makes use of the Internet and creates privacy for users through a series of security measures such as passwords, encryption and firewalls that work together to create a private network. Each network administrator creates his or her own way of combining the various security measures.
A VPN may be composed of a series of servers or sites that communicate with each other. The most common VPN is a remote-access VPN, which creates a secure tunnel from your computer to the your company's private network. In some cases, you don't even need Internet service. All you need is a computer, a phone line and a modem to call the server directly. But, to access the LAN, the network administrator might provide software that you install on your computer or provide instructions for configuring PPTP, or Point-to-Point Tunnelling Protocol. This will allow you to create a VPN between your computer and the company's private network. With your Windows operating system, PPTP is a standard component.