Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
A computer is just a box to hold some sand and bits of metal and plastic until you install an "Operating System" on it. That could be Windows or Mac or Linux or Android. If you build your own computer from scratch components, you have to buy and install an operating system. "All" boxes that come from computer builders include a factory installed operating system. These builders have volume purchasing deal with MS so they pay SIGNIFICANTLY less than the US$100+ retail price users have to pay. The operating system is just a collection of programs that tell the hardware what to do, and how to do it. Windows "comes with" some simple applications like Edge to connect to the internet, and Wordpad, or NotePad to create simple documents.
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Office is the marketing name of various "bundles" (groupings) of MS programs.
The Office bundle is sold independently of Windows.
Some computer builders include Office in the price of the computer. In the past that was an "OEM" type license that was permanently tied to the computer. More recently that has been a "free" subscription of Office 365 Personal. If they don't give you a "free" copy, builders are paid by MS to include a 30 day "free trial" of Office 365 for users to "play with".
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Bottom line, Office is not part of the computer, you have to buy it separately. One way or the other.