Microsoft cloud
M365
Microsoft 365
Microsoft 365, commonly abbreviated M365, is Microsoft's bundled productivity and security subscription suite. It combines the Office desktop and web applications (Word, Excel, PowerPoint, Outlook), cloud services (Exchange Online, SharePoint Online, OneDrive for Business, Microsoft Teams), and increasingly device and identity management services (Intune, Entra ID) under a single per-user licence.
Why M365 matters in a Microsoft estate
M365 matters because Microsoft 365, Azure, Windows 365, Teams, and related services are usually managed as one estate. The term connects to planning, cost, configuration, security, and day-two operational decisions across that estate.
How M365 shows up in practice
This replaces what was historically sold as separate Office, Exchange, and device management products. The suite is sold in distinct tiers aimed at different organisation sizes and needs. Business Basic, Business Standard, and Business Premium are aimed at organisations under roughly 300 users, with Business Premium notably adding Intune device management and Defender for Business. Enterprise E1, E3, and E5 are aimed at larger organisations, where E1 is cloud services without desktop Office apps, E3 adds desktop apps and baseline security and compliance, and E5 adds advanced security (Defender, Entra ID P2), compliance (Purview), and voice (Teams Phone) capabilities at a materially higher per-user cost.
This tiering structure is the single biggest source of licence waste in real Microsoft 365 estates. The temptation to standardise everyone on one SKU for administrative simplicity routinely results in E5 features being paid for and never activated for large portions of a user base that would be fully served by E3 or even Business Premium. Conversely, it can result in power users lacking capabilities they actually need because the organisation defaulted to a lower tier estate-wide. Licensing is assigned per user rather than per device, through the Microsoft 365 admin centre or automated via Entra ID group-based licensing. Each SKU unlocks a bundle of individual "service plans" that can be selectively disabled.
This is how organisations commonly turn off components like Yammer, Stream, or Power BI Pro that a licence technically includes but the business does not use. Because M365 licence cost scales linearly with headcount and tier, it is usually the largest single line item in a mid-sized organisation's Microsoft spend. It is also one of the most opaque to audit manually, since usage data (who is actually using Teams Phone, who has never opened SharePoint, who was assigned E5 for one feature and is otherwise idle) sits in different admin centres and reporting tools rather than one consolidated view. This is precisely the gap that licence optimisation and reclaim tooling is built to close.