What's the Difference?

Internet vs Intranet vs Extranet 

• Intranet is shared content accessed by members within a single organization.
• Extranet is shared content accessed by groups through cross-enterprise boundaries.
• Internet is global communication accessed through the Web

Internet

Though used on a daily basis by people all around the world, a thorough understanding of what the internet is lacking for most of its users. The internet can best be seen as a community of computers that are allowed to connect to each other, and any computer on the internet can connect any other computer at any time it wishes. Through infrastructure that spans the globe, there is one single, unified internet that all computers connect to, allowing anyone connected to share and access all the information that they choose to. While humans are often using computers in the traditional sense (with a mouse, keyboard, and monitor), many of the other ‘computers' we connect to are most often servers, which act as holding stations that store all the data that is being accessed.

The Internet functions via several major hubs throughout the world, where they connect and are able to connect to other major hubs. Primarily ordered and managed by the United States, a person sitting in California that is connected to the internet can access servers anywhere else around the world that are also connected. Because servers are physically located throughout the world, this is why some websites are able to return information faster than others - a server in a nearby city does not have to send data as far as a server thousands of miles away.

Intranet

Intranet is a restricted version of the internet, that typically does not allow access to anyone outside of its network. An intranet is typically a local only network, meaning only people who are directly wired to the intranet can access the information stored on its servers. Intranets may be used for organizations or networks that do not want their information to be able to be accessed by outside sources, and is especially important for organizations that require a high amount of secrecy - such as a server that holds military secrets or a database for the CIA. Intranets are basically mini versions of the internet that connect just a few servers, instead of the countless number of servers that the internet holds and connects with one another.

Extranet

Internet and an intranet are not always separate and clear cut, and anything that is a blend of the two is considered an extranet. An extranet is a private intranet (or local network) that is connected to the Internet, but only allows access to certain information or access by certain groups of people. The extranet is a blend of the secrecy and control allowed to an intranet, but also the convenience and sheer amount of information enjoyed by using the internet.

Extranets, however, are not perfect, and almost any network connected to the internet can be accessed inappropriately given enough time, motivation, and resources by an interested party. If a hacker with the right skill set decides to access an extranet, the question is more a matter of when they will be able to get past security measures and access it, rather than if they will be able to.