An Extranet is a private network that securely shares an organization's information or operations with its partners, suppliers, and consumers, partners through using Internet protocols, network connectivity and the public telecommunication system.
It can also be understood as a private intranet of a company that is not accessible for the public. An example is a military network that can access a common military radio transmission system without using the Internet. A private network mapped into a public one is what we call a VPN or a Virtual Private Network.
Some have argued”extranet" is just a buzzword for institutions interconnecting with each other to have their own private networks so they can share information. However, the difference with the extranet is that it’s connected through a shared network and not through a dedicated physical line.
In reference to the Internet Protocol networks, RFC 4364 states, "If all the sites in a VPN are owned by the same enterprise, the VPN is a corporate intranet. If the various sites in a VPN are owned by different enterprises, the VPN is an extranet. The term "site" refers to a distinct network environment not a website.
Furthermore, an extranet is used to describe selective access to the intranet systems. All it asks is some authentication for registered users so they can navigate. With this, it is important for an extranet to be fully secure and private. Programmers will definitely put firewalls, server management, and the encryption of messages and certificated for authentication to make sure that only those who can access it will be able to.
In early 2000s, the various industries used the extranet simply to share data with authorized members of particular work groups. For instance, project teams in the construction industry can log in and access the extranet to share documents, drawing, make comments or ask for further information. As years pass by, the uses of the extranet grows more and more. Companies can now exchange large volumes of data through Electronic Data Interchange, share-training programs and develop them together, share news of common interest with partner companies and many more.
On the other hand, extranets can be expensive in implementing and maintaining due to the software, hardware, training for employees and most importantly, the security needed to protect information and system accessibility. It can also lessen face-to-face meetings with customers and partners hence may reduce loyalty among partners.
