To get a sense of how the Internet, VPNs, Intranets, and Extranets compare the following Internet Standard Organizations within the context of e-business technology

1. IETF
2. IANA
3. W3C

Internet, Intranet, and Extranets are all special cases of TCP/IP-based networks. Intranets and Extranets use similar protocols and equipment as the Internet, but are limited in physical distribution, and by security hardware and software.

A virtual private network (VPN) allows the provisioning of private network services for an organization or organizations over a public or shared infrastructure such as the Internet or service provider backbone network. The shared service provider backbone network is known as the VPN backbone and is used to transport traffic for multiple VPNs, as well as possibly non-VPN traffic.
VPNs provisioned using technologies such as Frame Relay and Asynchronous Transfer Mode (ATM) virtual circuits (VC)^[1] have been available for a long time, but over the past few years IP and IP/Multiprotocol Label Switching (MPLS)-based VPNs have become more and more popular.
This book focuses on describing the deployment of IP- and IP/MPLS-based VPNs. The large number of terms used to categorize and describe the functionality of VPNs has led to a great deal of confusion about what exactly VPNs are and what they can do. The sections that follow cover VPN devices, protocols, technologies, as well as VPN categories and models.

Know where your control ends
Occasionally the Internet gets swamped, due to extremely important news or hype. Unfortunately, B2C and e-Commerce solutions cannot escape the performance variability of the Internet.
The architect's job for B2C, therefore, is to ensure that every network link (as well as the background server processing) leading up to the Internet for an e-Commerce solution can handle any peak use. The network links must also be manageable and reliable.
Defer to the buyer on ISPs (usually)
Most organizations have determined their plan of attack for Internet networking. It is generally implemented by:

1. The internal IT department
2. Outsourcing (typically ISPs)
3. A mixture of outsourcing and internal implementations

Larger organizations will often have a mixed networking solution. Most organizations are experiencing a gradual move towards internal networking and this progression is slow as many organizations determine that they cannot match ISP-provided reliability and throughput for the same price.
E-Commerce solutions may need to deviate from corporate preferences. In situations where time-to-market pressures dictate rapid deployment, use of an ISP will often facilitate the project.

[1]virtual circuit: A (VC) virtual circuit is a means of transporting data over a packet-switched network in such a way that it appears as though there is a dedicated physical link between the source and destination end systems of this data. The term virtual circuit is synonymous with virtual connection.