Illustrate the term Extranet?

Extranet:

Extranet is Extension of an Intranet that makes thelatter accessible to outside companies or individuals with or without an intranet. It is also defined as a collaborative Internet connection with other companies and business partners. Parts of the Intranet are made available to the customers or business partners forspecific applications. The Extranet is thus an extended Intranet, which isolates business communication from the Internet through secure solutions. Extranets provide the privacy and security of an Intranet while the global reach of the Internet.