Key difference: The Internet is the massive global system that connects computer networks around the world together. Millions of private, public, academic, business, and government networks worldwide connect with each other over the internet to share massive amounts of information, resources and services. Extranet, on the other hand, is an internal network that can be accessed externally. The extranet can be thought as an extension of the company’s intranet. People from outside the company can have a limited access to the company’s internal network for business or education related purposes.

The Internet is the massive global system that connects computer networks around the world together. Millions of private, public, academic, business, and government networks worldwide connect with each other over the internet to share massive amounts of information, resources and services. Internet is what we use to access web pages, send e-mails, listen to music or watch videos online. It hosts an extensive range of information, one that we generally take for granted today

The Internet uses the standard Internet protocol suite (TCP/IP) to allow us to connect to the net. It has numerous information resources and services, such as the web pages of the World Wide Web (WWW), games, videos, images, e-mail, social networking, etc. It has even spawned new services such as Voice over Internet Protocol (VoIP) and Internet Protocol Television (IPTV). The Internet is currently being used by billions of people worldwide.

The Internet carries information from all streams; traditional, such as newspaper, book and other print publishing; and modern such as blogging and web feeds. It also enabled new forms of human interactions through, instant messaging, e-mail, Internet forums, and social networking. It has gained so much popularity that in fact almost all forms of business communication as well as personal happens online through e-mail, instant messaging and social networking. With phone calls and text messaging (SMS) coming is second.

Extranet, on the other hand, is an internal network that can be accessed externally. The extranet can be thought as an extension of the company’s intranet. People from outside the company can have a limited access to the company’s internal network for business or education related purposes. The access may be granted to the organization’s partners, vendors, suppliers, current and potential customers, etc.

Webopedia defines extranet as “a buzzword that refers to an intranet that is partially accessible to authorized outsiders. Whereas an intranet resides behind a firewall and is accessible only to people who are members of the same company or organization, an extranet provides various levels of accessibility to outsiders. You can access an extranet only if you have a valid username and password, and your identity determines which parts of the extranet you can view.”

Webopedia also states that the extranets are becoming a very popular means for business partners to exchange information. However, the extranets require security and privacy, so that the information on the network is not wrongly accessed or misused by external parties. In order to protect the network, the extranets can incorporate firewall server management, the issuance and use of digital certificates or similar means of user authentication, encryption of messages, and the use of virtual private networks (VPNs) that tunnel through the public network.

SearchEnterpriseWAN lists some of the uses of the extranet:

• Exchange large volumes of data using Electronic Data Interchange (EDI)
• Share product catalogs exclusively with wholesalers or those "in the trade"
• 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
• Share news of common interest exclusively with partner companies

The main difference between the Internet and an extranet is that the Internet is open to all and everyone has equal and complete access to it. Whereas, the extranet provides limited access and to a limited group of people.

Image Courtesy: internet-turbo.com, etutorials.org