Internet, Intranet ,and Extranet

Question: what is meaning of Internet, Intranet ,and Extranet ?
Ans:-The Internet is an open, public space, while an intranet is designed to be a private space. An intranet may be accessible from the Internet, but as a rule it's protected by a password and accessible only to employees or other authorized users.
From within a company, an intranet server may respond much more quickly than a typical Web site. This is because the public Internet is at the mercy of traffic spikes, server breakdowns and other problems that may slow the network. Within a company, however, users have much more bandwidth and network hardware may be more reliable. This makes it easier to serve high bandwidth content, such as audio and video, over an intranet.
Extranet:-The Extranet is a portion of an organization's Intranet that is made accessible to authorized outside users without full access to an entire organization's intranet.