An intranet is something like a private network that can be accessed only by the staff of an organization. Depending on the nature and size of the organization and the extent of efforts it has taken for establishing a network of this kind, a wide range comprising of services and information from the internal information and technology systems of an organization are made available to the networked professionals which would not be accessible to the users of the internet at large. A network such as this has a huge and most vital role to play in facilitating the internal communication and as well as collaboration by providing a single point for accessing external and internal resources.
Popular examples of intranet include Local Area Networks or LAN or Wide Area Networks like WAN. These networks started appearing in larger and affluent organizations from the year 1994. The technology was made available to a wider market by the introduction of the free web-server from market leader Microsoft, in the year 1996.
These in-house networks are now being used as culture changing programs in corporate houses. For instance, employees today can discuss internal problems with concerned people on this internal network thus facilitating easy problem solving.