VPN is an abbreviation for Virtual Private Network, which means a “virtual LAN” that connects LANs together as a single LAN.

For example, if you have an internal LAN at the head office and at a branch office, you can only access data within the head office and branch office. However, by building a VPN, you can access and edit data at the branch office from the head office, and access and edit data at the head office from the branch office, etc., with a secure connection.