4.1 Word, Excel, PowerPoint, and OneNote

Quick Answer: Pick the app from the deliverable. Word = documents. Excel = analysis and charts. PowerPoint = slide decks. OneNote = notebooks. The same file can be created or edited in the desktop app, Microsoft 365 Apps for the web, or a mobile app. Co-authoring and AutoSave work when the file lives in OneDrive or SharePoint. Microsoft 365 Apps for enterprise is the work desktop suite — not Microsoft 365 Family, and not Microsoft 365 E5 by itself.

MS-900 does not ask you to pass a Microsoft Office Specialist exam. It asks a simpler, more valuable question: given a work product, which Microsoft 365 app is the right tool — and how do people actually create and share that product across devices?

The official skill is to describe the productivity and content creation capabilities of the core Microsoft 365 Apps: Microsoft Word, Microsoft Excel, Microsoft PowerPoint, and Microsoft OneNote. Outlook, Teams, Access, and Publisher exist in the broader suite. This bullet is about those four creation apps.

Desktop, web, and mobile — same apps, three surfaces

Microsoft 365 Apps is Microsoft's subscription name for the familiar Office client suite. Official Learn content is explicit on a point that still trips fundamentals candidates: the desktop apps are not a web application you rent by the hour. Users download them from the Microsoft 365 portal and install them on Windows, Mac, iOS, and Android. They run locally. Users do not need a constant internet connection to draft a document on a plane. They do need to connect periodically so the subscription can be verified — official guidance is at least once every 30 days — or the apps enter reduced functionality mode (open and view existing files, but most editing features stop).

That desktop install is Microsoft 365 Apps, not "Office running as infrastructure as a service." Installing Word on a laptop does not turn Microsoft 365 into IaaS. The service you subscribe to is still software as a service; the client happens to run locally.

Microsoft 365 Apps for the web (historically Office for the web / Office Online) is a different surface. Official service descriptions say Office for the web opens Word, Excel, OneNote, and PowerPoint documents in a web browser. The web versions are included with all Microsoft 365 and Office 365 plans, including plans that do not include the full desktop suite — for example Microsoft 365 Business Basic and Office 365 E1. A frontline worker on a kiosk browser can still open a Word file. A knowledge worker with Microsoft 365 Apps for enterprise can flip between the full desktop client and the browser on a borrowed PC.

Mobile apps (Word, Excel, PowerPoint, OneNote, and the Microsoft 365 app) cover phones and tablets. Official plan tables list Office Mobile for iPad/iPhone and Android on the subscription plans that include mobile rights. Some entry-level web-and-mobile plans historically limited full editing on larger-screen devices. The exam-safe statement is: mobile apps exist so people can view and edit on the go, and the richest desktop feature set still lives in the installed Windows or Mac client.

One Microsoft 365 work identity signs into all three surfaces. A file saved to OneDrive or a SharePoint library is the same file whether you open it in Word on Windows, Word for the web, or Word on a phone.

Which app for which job

Memorize the deliverable, not the ribbon.

Word is the document processor. If the scenario says draft a policy, write a proposal, track changes on a contract, or produce a formatted report, Word is the answer.

Excel is the analysis and charting app. If the scenario says forecast, calculate, chart quarterly results, clean a table, or model a budget, Excel is the answer. Excel can hold text, but that does not make it Word.

PowerPoint is the presentation app. If the scenario says present to leadership, build a customer pitch, or deliver training slides, PowerPoint is the answer. You can embed an Excel chart in a slide; the deck still belongs to PowerPoint.

OneNote is the free-form notebook. Notebooks have sections and pages. People clip web research, ink on a tablet, drop in images, and tag follow-ups. OneNote Class Notebook (education) adds a content library, a collaboration space, and a private notebook per student — useful color for education scenarios, not a reason to pick OneNote for a legal contract.

Enterprise work apps versus consumer Microsoft 365

Microsoft 365 Apps for enterprise (formerly Office 365 ProPlus) is the always-updated desktop suite for work. Official service descriptions call out intelligent features such as Ideas in Excel and real-time collaboration, plus a user-based license that can install Office on up to five PCs or Macs, five tablets, and five phones, with OneDrive storage for access from anywhere. Microsoft 365 Apps for business is the small-business sibling of the same idea.

That product is not:

• The complete Microsoft 365 E3/E5 suite. Windows Enterprise, Intune, and the broader security stack live on the suite, which you met in Chapter 2.
• Microsoft 365 Personal or Microsoft 365 Family, which are consumer home subscriptions. Family is designed to be shared in a household (up to six people). Neither is a work tenant with an organizational admin center.

Microsoft 365 Apps for the web still appears for consumer and commercial users. The exam trap is treating "I opened Word in a browser at office.com" as proof of a desktop-apps license — or treating a Family subscription as Microsoft 365 E3.

Co-authoring and AutoSave

Co-authoring means more than one person edits the same cloud file at the same time and sees others' changes. Official Microsoft 365 Apps messaging lists real-time collaboration as a reason organizations buy the subscription suite instead of a perpetual Office disc.

Co-authoring is not magic that works on any file path. The practical rule MS-900 wants:

1. Store the file in OneDrive (including OneDrive for work or school) or a SharePoint library (including a Teams files tab, which is SharePoint underneath).
2. Open it in a current Word, Excel, PowerPoint, or OneNote client — desktop, web, or mobile.
3. Leave AutoSave on.

AutoSave is the continuous save switch that appears in the desktop apps when the file is in OneDrive or SharePoint. When AutoSave is on, each change is written to the cloud copy. That is what lets two product managers edit the same Word brief without emailing Proposal_FINAL_v7.docx around. If AutoSave is off, or the file lives only on a local Documents folder or a USB stick, you are back to manual Save and you do not get true cloud co-authoring.

People can still comment, @mention, and share a link from the app. Sharing a OneDrive or SharePoint link is the modern replacement for attaching a copy. Attachments create forks; cloud links keep one copy.

A few exam-adjacent caveats, without turning this into a support article:

• Co-authoring quality is best on current Microsoft 365 Apps, not ancient perpetual Office.
• Files encrypted with some sensitivity labels historically opened in exclusive mode on desktop until an admin enabled co-authoring for encrypted files. If a scenario says "the file is labeled and only one person can edit," think protection settings — not "Word cannot co-author."
• OneNote co-authors at the notebook and page level because a notebook is already a syncing container, typically stored in OneDrive or SharePoint.

You do not need everyone on the same device type. One author can be in Word for the web in a hospital browser; another can be in the desktop app at headquarters; a third can fix a typo on a phone. The cloud file is the source of truth.

What MS-900 is really testing

Translate the scenario before you look at the choices.

• "Create a 10-page vendor contract with tracked changes" → Word
• "Chart last quarter's regional sales and highlight outliers" → Excel
• "Build a 15-slide board update with speaker notes" → PowerPoint
• "Keep a shared research notebook for the design sprint" → OneNote
• "Three people must edit the same file at once, and nobody should email copies" → store it in OneDrive or SharePoint, use AutoSave and co-authoring
• "Users need Word on a PC that is sometimes offline" → desktop Microsoft 365 Apps, not web-only
• "Users need to open Word in a browser and the plan has no desktop apps" → Microsoft 365 Apps for the web (Business Basic / Office 365 E1 style plans)
• "A household of six wants Word at home" → Microsoft 365 Family, not Apps for enterprise

Exam traps

• Do not study MOS click-paths. The exam will not ask which ribbon tab holds Mail Merge.
• App mismatch is the common miss. A presentation to the CFO is PowerPoint even if the numbers came from Excel.
• AutoSave is not a local-disk feature. It rides on OneDrive or SharePoint.
• Microsoft 365 Apps for enterprise is not Microsoft 365 E5 and is not Microsoft 365 Family. Apps for enterprise is the work desktop suite. E5 is the full platform. Family is consumer.
• Web apps are not a lesser product you only get if you paid for desktop. They ship with Microsoft 365 and Office 365 plans, including several that omit the desktop install.
• Installing the desktop apps does not change the cloud model. Microsoft 365 remains SaaS.