An intranet is a computer network for sharing corporate information, collaboration tools, operational systems, and other computing services only within an organization, and to the exclusion of access by outsiders to the organization. The term is used in contrast to public networks, such as the Internet, but uses most of the same technology based on the Internet Protocol Suite.^[1]

A company-wide intranet can constitute an important focal point of internal communication and collaboration, and provide a single starting point to access internal and external resources. In its simplest form, an intranet is established with the technologies for local area networks (LANs) and wide area networks (WANs).^[2][3][4] Many modern intranets have search engines, user profiles, blogs, mobile apps with notifications, and events planning within their infrastructure.

An intranet is sometimes contrasted to an extranet. While an intranet is generally restricted to employees of the organization, extranets may also be accessed by customers, suppliers, or other approved parties.^[5] Extranets extend a private network onto the Internet with special provisions for authentication, authorization and accounting (AAA protocol).

Increasingly, intranets are being used to deliver tools, e.g. collaboration (to facilitate working in groups and teleconferencing) or sophisticated corporate directories, sales and customer relationship management tools, project management etc.,

Intranets are also being used as corporate culture-change platforms. For example, large numbers of employees discussing key issues in an intranet forum application could lead to new ideas in management, productivity, quality, and other corporate issues.

In large intranets, website traffic is often similar to public website traffic and can be better understood by using web metrics software to track overall activity. User surveys also improve intranet website effectiveness.

Larger businesses allow users within their intranet to access public internet through firewall servers. They have the ability to screen messages coming and going, keeping security intact. When part of an intranet is made accessible to customers and others outside the business, it becomes part of an extranet. Businesses can send private messages through the public network, using special encryption/decryption and other security safeguards to connect one part of their intranet to another.

Intranet user-experience, editorial, and technology teams work together to produce in-house sites. Most commonly, intranets are managed by the communications, HR or CIO departments of large organizations, or some combination of these.

Because of the scope and variety of content and the number of system interfaces, intranets of many organizations are much more complex than their respective public websites. Intranets and their use are growing rapidly. According to the Intranet design annual 2007 from Nielsen Norman Group, the number of pages on participants' intranets averaged 200,000 over the years 2001 to 2003 and has grown to an average of 6 million pages over 2005–2007.^[6]

Most organizations devote considerable resources into the planning and implementation of their intranet as it is of strategic importance to the organization's success. Some of the planning would include topics such as determining the purpose and goals of the intranet,^[13][14] identifying persons or departments responsible for implementation and management and devising functional plans, page layouts and designs.^[15]

The appropriate staff would also ensure that implementation schedules and phase-out of existing systems were organized, while defining and implementing security of the intranet and ensuring it lies within legal boundaries and other constraints. In order to produce a high-value end product, systems planners should determine the level of interactivity (e.g. wikis, on-line forms) desired.

Planners may also consider whether the input of new data and updating of existing data is to be centrally controlled or devolve. These decisions sit alongside to the hardware and software considerations (like content management systems), participation issues (like good taste, harassment, confidentiality), and features to be supported.^[16]

Intranets are often static sites; they are a shared drive, serving up centrally stored documents alongside internal articles or communications (often one-way communication). By leveraging firms which specialise in 'social' intranets, organisations are beginning to think of how their intranets can become a 'communication hub' for their entire team.^[17] The actual implementation would include steps such as securing senior management support and funding.,^[18] conducting a business requirement analysis and identifying users' information needs.

From the technical perspective, there would need to be a co-ordinated installation of the web server and user access network, the required user/client applications and the creation of document framework (or template) for the content to be hosted.^[19]

The end-user should be involved in testing and promoting use of the company intranet, possibly through a parallel adoption methodology or pilot programme. In the long term, the company should carry out ongoing measurement and evaluation, including through benchmarking against other company services.^[20][21]

Some aspects are non-static.

An intranet structure needs key personnel committed to maintaining the intranet and keeping content current. For feedback on the intranet, social networking can be done through a forum for users to indicate what they want and what they do not like.

A short item in "Top Five Intranet Trends for 2019"^[9] was titled Data Privacy concerns come to the intranet. Part of the force behind this is the European Union's General Data Protection Regulation which went into effect May 2018.

An enterprise private network is a computer network built by a business to interconnect its various company sites (such as production sites, offices and shops) in order to share computer resources.

Beginning with the digitalisation of telecommunication networks, started in the 1970s in the USA by AT&T,^[23] and propelled by the growth in computer systems availability and demands, enterprise networks have been built for decades without the need to append the term private to them. The networks were operated over telecommunication networks and, as for voice communications, a certain amount of security and secrecy was expected and delivered.

But with the Internet in the 1990s came a new type of network, virtual private networks, built over this public infrastructure, using encryption to protect the data traffic from eaves-dropping. So the enterprise networks are now commonly referred to as enterprise private networks in order to clarify that these are private networks, in contrast to public networks.