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MS-900: Microsoft 365 Apps and Services

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Microsoft 365 Apps and Services

What this domain covers

Microsoft 365 is a subscription bundle of productivity apps and cloud services, not merely "Office online." Separate three layers. Apps: Word, Excel, PowerPoint, Outlook, Teams, and the Microsoft 365 Apps desktop client. Services: Exchange Online for mail, SharePoint Online for team sites and intranets, OneDrive for Business for per-user storage, Teams for chat and meetings, plus Planner, Lists, Bookings, and Viva for work management. Platform: Entra ID, Intune, and Defender, which are what make Microsoft 365 broader than Office 365. Office 365 is a subset: apps and core services without the full identity, device, and security stack. Also distinguish Windows 365 (a Cloud PC) from Azure Virtual Desktop (customer-managed VDI).

Traps

Questions often test where content lives. OneDrive for Business is per-user; SharePoint is shared team content; files in Teams channels are stored in SharePoint, while files in private chats live in OneDrive. "Microsoft 365 Apps" is the subscription desktop client, not a plan. Desktop rights vary: Business Basic is web and mobile only, Business Standard adds desktop apps, and Business Premium adds security and device management. Web and mobile app versions are broadly included, but full desktop rights are plan-dependent.

Worked example

A 60-person firm needs desktop Office, hosted email, Teams, and basic device management. Business Premium fits: it is under the 300-seat cap and bundles the apps with Intune and Defender for Business.

Rule of thumb: if the need is only apps and mail, think Office 365; if it adds identity, device, or threat protection, think Microsoft 365.