Microsoft Knowledge Base Article 305550 contains the following introduction:
This step-by-step article describes how to configure a virtual private network (VPN) connection to your corporate network in
Microsoft Windows XP Professional. A VPN connection is a connection that uses both private and public networks to create a
Both Point-to-Point Tunneling protocol (PPTP) or Layer Two Tunneling Protocol (L2TP) are automatically installed on your Windows XP-based computer. These protocols help provide security when you access resources on a network by connecting to a remote access server through the Internet or other network. This kind of connection is known as a VPN connection.