The terms intranet, Internet, and extranet are often used interchangeably; however, there are some important differences between them. To better understand these differences, it is useful to look at the prefixes.
The prefix intra means within, inter means between, and extra means beyond. So how does this translate to online-based networks?
Basically, the Internet is an open entity that anyone in the world can access. It is open to everyone who has a working computer or device and appropriate Internet access.
An intranet is a private network that is typically limited to authorized users.
For example, most major organizations operate some form of intranet that only employees of the business can access and use. Intranets are usually employed to support a corporate culture and objectives and provide a platform on which employees can share information, communicate, collaborate, and network.
They are generally faster than the Internet because the information is stored on local network servers as opposed to being accessed from data centers throughout the world.
An extranet combines some elements of both the Internet and intranet. It is open to people both within and outside an organization; however, only people who have pre-arranged authorization can access it. An extranet is a restricted network that some, but not all, members of the public can access. A company may develop an extranet to create a mechanism by which it can connect with suppliers, customers, and other external agencies without making the content visible to the general public.