The cloud and Microsoft 365, explained simply

“The cloud” sounds mysterious, but the idea is simple: it’s someone else’s computers, which you rent over the internet. Instead of buying and running your own email server, for example, you pay Microsoft or Google to run it for you.

Why everyone moved there

• No hardware to buy, house or replace.
• Pay as you go, usually per user per month.
• Access from anywhere, on any device.
• The provider handles power, cooling, hardware failures and much of the security of their data centers.

The trade-offs: you depend on your internet connection and the provider, ongoing costs add up, and you are still responsible for how you set it up, as we’ll see.

The three kinds of cloud service

Type	What you rent	Examples	What you still manage
SaaS (software as a service)	A finished application	Microsoft 365, Google Workspace, Zoom	Users, settings, your data
PaaS (platform as a service)	A ready-made place to run your apps	Website and app hosting platforms	Your app and its data
IaaS (infrastructure as a service)	Virtual servers, storage and networks	Microsoft Azure, Amazon Web Services, Google Cloud	Nearly everything above the hardware

Most small offices live almost entirely in SaaS, so that’s where to start.

Microsoft 365: what’s in the box

Microsoft 365 is a bundle of cloud services that a huge share of businesses run on. The pieces you’ll support most:

• Exchange Online: email and calendars (what Outlook connects to)
• OneDrive: each person’s own cloud file storage
• SharePoint: shared team and company files
• Teams: chat, meetings and calls
• The Office apps: Word, Excel, PowerPoint and Outlook

Google’s equivalent is Google Workspace (Gmail, Drive, Docs and Meet). The concepts carry over almost one for one.

Entra ID: the keys to everything

Behind Microsoft 365 is Microsoft Entra ID (formerly called Azure Active Directory). It’s the list of users, passwords, groups and sign-in rules for the whole organization. If you’ve built a Windows domain in your home lab (step 7), it’s the cloud cousin of Active Directory. Many offices connect the two so people use one password for both.

This is where cloud security is won or lost:

• Turn on two-step sign-in for everyone (step 5). For Microsoft 365, the free security defaults setting turns it on across the whole organization.
• Give admin rights only to people who need them, and use separate admin accounts.

The shared responsibility model

This is the most misunderstood part of the cloud. The provider secures its data centers and services; you secure how you use them. Microsoft keeps Exchange running, but if an employee’s password gets phished and there’s no two-step sign-in, that’s on the customer, not Microsoft.

The same goes for backups. Cloud services protect against their hardware failing, but deletions, ransomware syncing through OneDrive, and departing employees can still cost you data. Many organizations add a separate backup for Microsoft 365.

Try this

If you have a Microsoft account, explore account.microsoft.com, or with a Google account, myaccount.google.com. Look at the security sections: sign-in methods, recent activity and connected devices. Those are the same kinds of settings you’ll manage for whole organizations.

Key takeaways

• The cloud is rented computers: SaaS rents apps, PaaS rents platforms, and IaaS rents servers.
• Microsoft 365 (Exchange, OneDrive, SharePoint, Teams) runs a huge share of offices, and Entra ID is its identity system.
• Shared responsibility: the provider runs the service, and you secure the accounts and data.