The direct answer
All three use the same internet technology. What separates them is the audience and the door. The internet is open to anyone. An intranet is closed to everyone except the organization's own people. An extranet is a guarded side door: named outsiders get into a defined area, and nothing else.
| Internet | Intranet | Extranet | |
|---|---|---|---|
| Who it is for | Anyone | Employees and contractors of one organization | Named partners, suppliers, customers or agencies |
| Access | Public, no sign-in | Organization sign-in | Guest or partner sign-in, limited to invited areas |
| Typical content | Marketing site, public services | News, policies, department sites, tools, search | Shared projects, documents, orders, tickets |
| Who controls content | Every publisher on the web | The organization | The organization, with partners contributing where allowed |
| Main risk | Public exposure | Stale content and oversharing inside | Over-broad guest access |
Definitions that hold up
The NIST Computer Security Resource Center glossary takes its definitions from IETF RFC 4949. It defines the internet as the single interconnected worldwide system of commercial, government, educational and other networks that share the Internet Architecture Board's protocols and ICANN's name and address spaces; an intranet as a network, especially one based on internet technology, that an organization uses for its own internal and usually private purposes; and an extranet as a network an organization uses for traffic between itself and its business partners.
What a modern intranet is made of
Microsoft describes an intranet as possibly including the organization's main landing page, portals for corporate communications and sites for departments such as IT or HR (Microsoft Learn, accessed 2026-11-11). In Microsoft 365 that means SharePoint communication sites for news and policy, team sites for departments, navigation and search across them, news targeted to audiences, and Teams as the place people already work. Microsoft contrasts the old intranet, communication by email and a hierarchy of static sites, with one where news is personalized and community content lives in Viva Engage.
Microsoft's own list of success factors is practical: tie the intranet to business outcomes, have an executive sponsor and champions, set KPIs, design for simplicity, write a governance plan for roles, compliance, retention and site provisioning, audit content before migrating it, and train content owners. It also warns that an intranet is never done: without a plan to keep content current, it loses value from launch day.
How an extranet works in Microsoft 365
Microsoft Learn describes a SharePoint extranet as a site external partners use to reach specific content and collaborate, with only the content and access they need, instead of emailing documents back and forth. In Microsoft 365, partners connect to a members-only SharePoint site, a team in Microsoft Teams or a Teams shared channel, without access to the on-premises environment or to any other teams or sites.
- Owner-approved sharing. Sharing through Microsoft 365 Groups or Teams stops members from inviting new guests without approval.
- One site per partner. Partner users can be restricted to a single site or team and cannot search for or see content elsewhere.
- Audit. Who invited whom, and when a guest signed in, can be searched in the Microsoft Purview audit log.
- Data protection. Microsoft points to Purview Data Loss Prevention and Defender for Cloud Apps for a secure guest-sharing environment.
Compared with an on-premises extranet, Microsoft lists no firewall access for guests, no complex network configuration, no extra hardware and minimal ongoing maintenance (Microsoft Learn, accessed 2026-11-11).
Which one do you need?
- Telling the public who you are: a website on the internet.
- Giving employees one place for news, policies, tools and search: an intranet.
- Working on files and projects with people outside the company: an extranet, scoped per partner.
- Serving many external users with forms or self-service: often a portal on Power Pages rather than shared SharePoint sites.
Where EPC Group helps
EPC Group plans and builds SharePoint intranets and partner extranets in Microsoft 365: the information architecture and navigation, the home site and department sites, news and audience targeting, the governance plan for owners, retention and provisioning, and the guest-access model that keeps each partner inside its own site. See SharePoint intranet consulting, how an intranet works on SharePoint and secure partner and customer portals.
Primary sources
- Internet (glossary) — NIST CSRC, from IETF RFC 4949, accessed 2026-11-11
- Intranet (glossary) — NIST CSRC, from IETF RFC 4949, accessed 2026-11-11
- Extranet (glossary) — NIST CSRC, from IETF RFC 4949, accessed 2026-11-11
- Intelligent intranet introduction (SharePoint in Microsoft 365) — Microsoft Learn, accessed 2026-11-11
- Use SharePoint as a business-to-business (B2B) extranet solution — Microsoft Learn, accessed 2026-11-11
Frequently Asked Questions
What is the main difference between an intranet and the internet?
Audience and access. The internet is the single worldwide system of interconnected public networks; an intranet is a network an organization uses for its own internal, usually private, purposes (NIST CSRC glossary, from IETF RFC 4949). Anyone can reach a public website; only the organization's signed-in people can reach its intranet.
What is an extranet?
A network an organization uses for traffic between itself and its business partners (NIST CSRC glossary, from IETF RFC 4949). In Microsoft 365, Microsoft describes a SharePoint extranet site as one you create so external partners can reach specific content and collaborate, with only the content and access they need (Microsoft Learn, accessed 2026-11-11).
Is an intranet the same as a company website?
No. A company website is public and sits on the internet for customers and prospects. An intranet is for employees: news, policies, department sites, tools and search across internal content. Many organizations run both, and an extranet in between for partners.
Can an intranet be reached from outside the office?
Yes, when it is cloud-hosted. A SharePoint intranet in Microsoft 365 is reached over the internet but only after sign-in, so it stays private while working from anywhere. Older on-premises intranets usually needed a VPN or the corporate network.
Do you need separate software for an extranet in Microsoft 365?
No. Microsoft states that partners connect directly to a members-only SharePoint site, a team in Microsoft Teams or a Teams shared channel, without access to the on-premises environment or to other teams and sites, and that no other hardware is required (Microsoft Learn, accessed 2026-11-11).
Talk to a senior architect
A one-hour call with a senior EPC Group architect covers what your intranet should hold, how partners should reach shared work, and how to govern both. Email contact@epcgroup.net or call 888-381-9725.
Documented and anonymized engagements
Named engagements come first; anonymized summaries follow under the anonymized-engagement rule — the client is not named and every statement is EPC-reported. Documents behind named engagements are in the Evidence Center.
- Samsung Semiconductor, Inc. — SharePoint Server 2019 build and deployment: custom user experience, navigation, web parts, search, enterprise-application integration, quality assurance and training (2021)Samsung Semiconductor, Inc. · 2021 · Contracted — countersigned
- Canadian Forces Morale & Welfare Services (CFMWS) — SharePoint consulting support (2014)Canadian Forces Morale & Welfare Services (CFMWS) · 2014 · Contracted
- Stryker Corporation — SharePoint Center of Excellence development (2012)Stryker Corporation · 2012 · Delivered — payment-corroborated (client payment records published)
- Federal Reserve Bank of New York — SharePoint best-practices needs assessment, architecture and governance gap analysis, roadmap for a global SharePoint Center of Excellence across the twelve Reserve Bank districts (2010)Federal Reserve Bank of New York · 2010 · Contracted — countersigned, with historical work product
- Copilot and SharePoint AI Governance: Regional Bank (2024)Anonymized engagement summary · Regional bank · 2024Engagement phase: governance and readiness planning before a Copilot rollout; no rollout is reported
- SharePoint Intranet Permission Automation: Contractor (2024)Anonymized engagement summary · Federal government contractor · 2024
- Two SharePoint Farms to SharePoint Online: Regional BankAnonymized engagement summary · Regional bank · 2024
- SharePoint Health Check, Upgrade and Support: ManufacturerAnonymized engagement summary · Consumer-products manufacturer · 2017–2023
More engagements: NASA (agency-wide, across the NASA Centers) — Agency SharePoint Phase 1 Initiative: needs assessment, architectural review, governance, and a global SharePoint Center of Excellence for knowledge management, intranet and enterprise content management across the NASA Centers (2009–2010) · National Archives and Records Administration (NARA) — SharePoint records management and Center of Excellence advisory and implementation support (2010) · National Institutes of Health — SharePoint Center of Excellence design (2010) · Northrop Grumman — 'Finance I.R.M. Automation Process' statement of work on SharePoint (2010) · NASA Johnson Space Center — SharePoint Site Provisioning Solution (2009) · YMCA (Houston) — Microsoft Office SharePoint Server 2007 implementation (2007) · SharePoint Support and Custom Apps: Professional Services · SharePoint 2010 to 2019 Migration: Regional Bank (2020) · SharePoint Online Document Management: Transportation (2020) · SharePoint 2010 to Online Design: Global Law Firm (2018) · SharePoint 2016 Intranet Redesign: Energy Company (2018) · SharePoint Intranet Redesign: Financial Services · SharePoint Migration: Major Healthcare Network