what is 'intranet and extranet'?

Answer 1

Intranet:
is a private computer network that uses Internet protocols, network connectivity, and possibly the public telecommunication system to securely share part of an organization's information or operations with its employees.

Extranet:
is a private network that uses Internet protocols, network connectivity, and possibly the public telecommunication system to securely share part of an organization's information or operations with suppliers, vendors, partners, customers or other businesses.

The main difference is if information is shared "internally" within the company/organisation or "externally" with partners and other parties.

Answer 2

An intranet is an information portal designed specifically for the internal communications of small, medium or large businesses, enterprises, governments, industries or financial institutions of any size or complexity. Intranets can be custom-designed to fit the exact needs of businesses no matter where they are situated. Users of intranets consists mainly of:

Members of the executive team.
Accounting and order billing.
Managers and directors.
Sales people and support staff.
Customer service, help desk

An extranet is somewhat very similar to an intranet. Extranets are designed specifically to give external, limited access to certain files of your computer systems to:

Certain large or priviledged customers.
Selected industry partners.
Suppliers and subcontractors

Intranets and extranets all have three things in common:

They both use secured Internet access to the outside world.
Both can drastically save your company or organization a lot of money.
Both need a user ID & password to control access to the whole system.