An extranet is a controlled private network that allows access to partners, vendors and suppliers or an authorized set of customers – normally to a subset of the information accessible from an organization’s intranet. An extranet is similar to a DMZ in that it provides access to needed services for authorized parties, without granting access to an organization’s entire network. An extranet is a private network organization.
Historically the term was occasionally also used in the sense of two organizations sharing their internal networks over a VPN.
During the late 1990s and early 2000s, several industries started to use the term ‘extranet’ to describe centralized repositories of shared data (and supporting applications) made accessible via the web only to authorized members of particular work groups – for example, geographically dispersed, multi-company project teams. Some applications are offered on a software as a service (SaaS) basis.
- Exchange large volumes of data using Electronic Data Interchange (EDI)
- Share product catalogs exclusively with trade partners
- Collaborate with other companies on joint development efforts
- Jointly develop and use training programs with other companies
- Provide or access services provided by one company to a group of other companies, such as an online banking application managed by one company on behalf of affiliated banks.
- Extranets can be expensive to implement and maintain within an organization (e.g., hardware, software, employee training costs), if hosted internally rather than by an application service provider.
- Security of extranets can be a concern when hosting valuable or proprietary information.