What is Microsoft 365?

Microsoft 365 is Microsoft's subscription bundle of cloud-based productivity software. It combines the familiar desktop apps — Word, Excel, PowerPoint, and Outlook — with online services for email, file storage, collaboration, communication, identity, security, and increasingly AI. Where the older "Office" brand referred to a one-time-purchase set of desktop tools, Microsoft 365 is delivered as an ongoing service that updates continuously.

For most organisations of any real size, Microsoft 365 is the operating system of daily work — the place where email arrives, where documents live, where meetings happen, where identities sit. Getting the plan choice right, and understanding what each layer does, is one of the higher-leverage decisions in enterprise IT.

What you actually get

A typical business subscription includes:

Office apps. Word, Excel, PowerPoint, Outlook, and OneNote — both as installable desktop apps (Windows, macOS, iOS, Android) and in the browser. On the Business Basic tier, only the browser versions ship; on Standard and above, the desktop apps are included.

Email and calendaring. Exchange Online, with mailboxes and calendars hosted by Microsoft. Anti-spam, anti-phishing, and calendar-sharing are included; deeper anti-threat features (Safe Links, Safe Attachments) come with Defender for Office 365, which higher plans bundle.

File storage. OneDrive for personal files (1 TB per user standard, more with add-ons) and SharePoint for shared team libraries. Every Microsoft 365 group provisions a SharePoint site; every Teams team runs on top of one; documents co-authored in Word live in SharePoint or OneDrive without the user thinking about it.

Communication. Microsoft Teams for chat, meetings, calls, and increasingly telephony. Teams is the centre of gravity for daily work in a Microsoft 365 tenant.

Identity and access. Microsoft Entra ID (formerly Azure AD) for sign-in, groups, and permissions. Conditional Access on P1 tiers and above; Identity Protection and PIM on P2. Every Microsoft 365 plan includes some tier of Entra ID.

Security and management. Microsoft Defender (for endpoint, for Office, for identity, for cloud apps), Purview (for information protection, DLP, records management, insider risk), and Intune (for device and app management). The specific coverage varies materially by plan.

Automation and analytics. Power Automate, Power BI, and Power Apps on higher tiers — with meaningful capabilities for building business apps and workflows without leaving the Microsoft 365 stack.

Copilot. Not included in Microsoft 365 by default — Microsoft 365 Copilot is a $30/user/month add-on. Copilot Chat (the free tier) does come included with every Microsoft 365 SKU that includes Teams.

How the pieces connect

The point of buying these tools together — instead of stitching them together yourself — is that files, identities, and permissions flow between the apps without wiring anything up. A document drafted in Word can be co-edited in a Teams channel, stored in a SharePoint library, secured by Entra ID Conditional Access, protected by a Purview sensitivity label, and discoverable in Microsoft Search, all with no explicit configuration.

That "one stack" experience is the primary value proposition. It is also the primary lock-in — moving off Microsoft 365 to a competing suite is more painful than moving between individual products, because the integrations are what make the suite worth its price.

Behind every Team is a Microsoft 365 Group which provisions a shared mailbox, a SharePoint site, and a Planner plan. When you @mention someone, you're using their Entra ID identity. When you share a file from OneDrive, the sharing link runs through Entra CA. This cascade is what makes the platform coherent — and what makes governance a discipline in its own right, because everything is connected to everything.

Microsoft 365 vs Office 365

The "Microsoft 365" brand replaced "Office 365" in 2020, but Office 365 SKUs still exist alongside Microsoft 365 SKUs at the enterprise tier. The distinction is real:

Office 365 SKUs include the productivity apps and services (Exchange, SharePoint, Teams, OneDrive) but not the Windows licence or the endpoint management stack.

Microsoft 365 SKUs bundle Office 365 plus Windows plus enterprise mobility and security (Entra, Intune, Defender at various levels).

For an org that already licences Windows separately, Office 365 might be the right pick. For an org that wants everything from Microsoft under one licence, Microsoft 365 is the natural bundle. Business SKUs are Microsoft 365 only — the Office 365 / Microsoft 365 distinction applies at the Enterprise tier.

The plan families

Business (Basic, Standard, Business Premium). Up to 300 users. Business Basic is web-only; Standard adds the desktop apps; Business Premium adds Intune, Entra ID P1, Defender for Business, and Purview basics. Business Premium is the working baseline for SMBs that take security seriously.

Enterprise (F1, F3, E1, E3, E5, plus the Office 365 tier variants). No user cap. E3 is the enterprise workhorse (P1 identity, basic compliance, core Defender). E5 is the top-tier (P2 identity, full Defender, full Purview, Power BI Pro included, Teams Phone). F1 and F3 are for frontline / deskless workers on shared devices with browser-first workflows.

Frontline. F1 (web + email + Teams) and F3 (adds Windows and Intune). Cheaper per-seat pricing for shift workers, retail floor, warehouse operators, hospital wards.

Education. A1, A3, A5 — parallel to E1/E3/E5 but with education-specific pricing and features. Free A1 is available for many educational institutions.

Consumer. Microsoft 365 Personal, Family — for individuals and households. Includes Copilot Pro on some tiers. Not for businesses.

For most decisions the important choice is at the enterprise tier: E3 vs E5 for full-user roles, F1 or F3 for frontline roles, Business Premium for SMBs. The delta between E3 and E5 is $22/user/month at 2026 pricing — real money at scale, but justified when Compliance, Defender XDR, and P2 identity all matter.

Add-ons that matter

Add-ons layer on top of the base SKUs. The important ones:

Microsoft 365 Copilot ($30/user/month). Full Copilot inside the productivity apps grounded on work data. Deploy to a subset first — see the licensing guide.

Teams Phone ($8-$15/user/month depending on tier). Turns Teams into a full PBX with external phone numbers.

Teams Premium ($10/user/month). Advanced meeting features (custom branding, watermarks, intelligent recap without Copilot, webinars).

Entra Suite ($12/user/month on top of P1/P2). Bundles Internet Access, Private Access, Verified ID premium, ID Governance, Identity Protection.

Intune Suite ($10/user/month on top of Intune). Bundles EPM, Remote Help, Enterprise App Management, Tunnel for MAM, Advanced Endpoint Analytics, Cloud PKI.

Each add-on is a real subscription that has to be justified per user; they compound quickly. A well-managed enterprise tenant has an explicit inventory of which add-ons go to which user cohorts.

Common operational disciplines

Three that come up in every tenant of any size:

Licence management. Group-based licensing (P1+) assigns licences via Entra group membership, driven by HR data. Attach licensing reduces cost when users need multiple products. Licence reconciliation quarterly catches over-provisioning.

Governance of Groups, Teams, and Sites. Every new Team is a new Microsoft 365 Group is a new SharePoint site is a new mailbox. Left un-governed, tenants sprawl into tens of thousands of stale objects within a few years. Team creation controls, expiration policies, sensitivity labels, and SharePoint Advanced Management are the operational tools for keeping the estate healthy.

Copilot readiness. As Microsoft 365 Copilot rolls out, the questions "what data does Copilot see?" and "who has access to what?" surface every SharePoint permission mistake made in the past decade. Copilot rollout usually forces a permissions and labelling cleanup that had been deferred.

The short version

Microsoft 365 is Microsoft's cloud productivity suite, delivered as a subscription with continuous updates. It bundles Office apps, email, storage, collaboration, identity, security, and management — increasingly with AI on top. Business, Enterprise, Frontline, and Education plan families cover different customer shapes; add-ons layer on top for specific capabilities (Copilot, Phone, Entra Suite, Intune Suite).

For any org running Microsoft business apps, this is the operating system of daily work. Governance, licensing discipline, and Copilot readiness are the three operational stories that dominate the ongoing conversation.