By the end of this lesson you will be able to
- Explain in plain words what the cloud is and where your files really are.
- Describe how synchronisation keeps a local copy and a cloud copy matching, and what happens when a file is deleted.
- Explain why sync is not the same as a backup, and use version history and the bin to recover a file.
- Take simple steps to keep a cloud account and its files secure.
Many people say that their photographs are in the cloud as if they floated in the sky. They do not. They sit on real computers in buildings called data centres, owned by a company. Understanding this helps you decide what to put there, what to keep at home, and what to do when the cloud copy and the copy on your laptop disagree. This lesson explains cloud storage and synchronisation in plain language, with the steps for Ubuntu and Windows.
What the cloud really is
Cloud computing means using someone else's computers over the Internet. Cloud storage is the part of it that keeps your files on those computers. You reach them through an app or a website after logging in. It is like renting a safe deposit box in a bank. The bank looks after the building, the power and the repairs, and you can reach your box from many places, but the box is not in your house.
That arrangement has clear benefits. You can open a file from your laptop, your phone or a library computer. A broken laptop does not destroy files that are also stored online. You can share a file with a shared link instead of sending copies. It also has costs. You need an internet connection to reach files that are not stored on the device. Free accounts have a storage quota, and the provider's rules, prices and security now matter to you.
- Works with no internet
- You control the device
- Lost if the laptop is lost and nothing else exists
- Hard to reach from elsewhere
Fast and private
- Reachable from any device you log in on
- Survives a broken laptop
- Needs internet for files not on the device
- Depends on the provider and your account security
Convenient and shareable
Read this figure as text
Two columns comparing files stored on a laptop with files stored in the cloud.
Two columns. Local storage, files on your own device: works without internet; you control the device; lost if the device is lost, broken or stolen and there is no other copy; reaching it from another device is hard. Cloud storage, files on the provider's servers: reachable from any device with a login; survives the loss of one laptop; needs internet to get files that are not already on the device; depends on the provider and on the security of your account.
How synchronisation works
Synchronisation, or sync, keeps a folder on your device matching a folder in the cloud. When you add, change or delete a file in the synced folder, the sync program notices and copies that change to the other side. The same change then appears on every other device that is signed in to the account. The sync program runs quietly in the background. A small icon shows whether it is up to date, working or in trouble.
Read this figure as text
A sequence showing a file saved on a laptop, uploaded to the cloud, then downloaded to a phone.
Three actors: Laptop, Cloud, Phone. Message 1: Amina saves a change to report.docx in the synced folder on her laptop. Message 2: the sync program uploads the changed file from the laptop to the cloud. Message 3: the cloud tells the phone that a newer version exists. Message 4: the phone downloads the new version and now matches the laptop.
Sync is not the same as a backup
This is the most important idea in the lesson. A backup is a separate copy made so that you can recover from a loss. Because sync mirrors changes, a mistake, a deletion, a virus or ransomware that damages files on your laptop can be copied to the cloud. Then every copy is damaged. Cloud services help with this through version history: they keep earlier versions of a file for a time so that you can go back. That is useful but limited. For files that matter, keep a real backup as well, as the module on backups explained: one more copy on a separate drive, besides your laptop and the cloud.
- File deleted by accident
- Deletion copied everywhere
- Bin or versions for a limited time
- After that the file is gone
Risky for important files
- File deleted by accident
- Deletion copied everywhere
- Backup on a separate drive still has it
- Restore the file
Recoverable
Read this figure as text
A comparison of sync only and sync plus backup after a file is accidentally deleted.
Two columns. Sync only: you delete a file by accident; the deletion syncs to the cloud and to your other devices; you can recover it only from the bin or version history for a limited time; after that it is gone. Sync plus a separate backup: you delete a file by accident; the deletion syncs everywhere; the backup on an external drive still holds the file; you restore it from the backup.
Using cloud storage on Ubuntu and on Windows
The details depend on the provider and your system, so treat the steps below as a guide and expect small differences between releases. Do not install a sync program from a random website: use the provider's official page, or on Ubuntu the App Center.
Connecting to cloud storage
Menu names are for Ubuntu 24.04 with GNOME and Windows 11 and may differ slightly in other releases or provider apps.
Ubuntu does not include one single cloud sync program for every provider. A simple built-in route is Online Accounts, which lets the Files app show files from some providers (the list depends on the release). Other providers offer their own Linux app or a web browser interface. Cloud files shown in this way may be opened from the network instead of kept as a full local copy.
Add an online account in Ubuntu
Step 1: Open Settings
Open Activities, type Settings and press Enter.
You should see: The Settings window opens with a list of sections on the left.
Step 2: Choose Online Accounts
Select Online Accounts from the list on the left, then pick a provider that is listed. If your provider is not listed, use its website or its own Linux app instead.
You should see: A sign-in window from the provider appears.
Step 3: Sign in on the provider's own page
Check that the address shown is the provider's real one before you type a password. Use your own account only; never use a password of someone else.
You should see: After you allow access, the account appears in the Online Accounts list.
Step 4: Look in Files
Open Files. If the provider supports it, it appears in the sidebar and you can browse its folders.
You should see: You see the cloud folders listed, and opening a file may take a moment because it is fetched over the internet.
Windows 11 includes OneDrive, which links to a Microsoft account. When it is signed in, a OneDrive folder appears in File Explorer, and Windows can also keep your Desktop, Documents and Pictures folders in it if you choose. A cloud icon in the notification area at the right of the taskbar shows its state. Other providers have their own downloadable apps.
Check OneDrive in Windows 11
Step 1: Open File Explorer
Press Windows key + E, or select the folder icon in the taskbar.
You should see: File Explorer opens and you see your usual quick-access folders.
Step 2: Find the OneDrive folder
Look in the navigation pane on the left for OneDrive. Open it.
You should see: You see the folders that are synced with the cloud.
Step 3: Read the status icons
Beside each file or folder, a small icon shows its state: a cloud outline means it is online only, a green tick means it is stored on this device, and circling arrows mean that it is syncing.
You should see: You can say which of your files are online only and which are on the device.
Step 4: Choose what stays on the device
Right-click a file and select Always keep on this device to make it available offline, or Free up space to remove the local copy and keep it online only.
You should see: The icon changes to match your choice.
- Marker 1: Online only: needs internet
- Marker 2: On this device: works offline
- Marker 3: Syncing: wait for it to finish
Read this figure as text
A simulated file window listing files with online-only, on-this-device and syncing states.
A simulated file manager window titled Cloud folder. The sidebar has Cloud folder active and Documents. Row 1: holiday-photos, folder, online only. Row 2: budget-2026.xlsx, on this device. Row 3: report.docx, syncing. Marker 1 points to the first row, online only: the file is in the cloud and needs internet to open. Marker 2 points to the second row, on this device: a local copy exists, so it opens offline. Marker 3 points to the third row, syncing: changes are being copied, so wait before switching off the laptop.
Offline access and sync conflicts
Offline access means that you can open a file with no internet because a local copy is stored on the device. Before a journey, check that the files you need are marked as available on the device. Changes you make offline are uploaded when the connection returns.
A sync conflict happens when the same file is changed in two places before they could sync, for example on your laptop offline and on your phone. The service does not know which version is correct, so it usually keeps both and adds the device name or the word conflict to the file name. Open both, copy what you need into one file, and delete the other. To avoid conflicts, let sync finish before you close the laptop, and avoid editing the same file in two places at once.
Keeping a cloud account safe
- Protect the account with a unique passphrase and multifactor authentication. Whoever logs in can see everything in it.
- Check who a shared link is open to. Prefer sharing with named people over a link that anyone can open.
- Do not put very sensitive files, such as scans of identity documents, in a folder that is shared or synced to devices you do not control. If you must store them, consider encrypting them first.
- Watch your storage quota. When the account is full, new files may stop syncing. Delete what you do not need, and check that a full quota does not block your email.
- Read what happens to your files if you stop paying or stop using the account. Providers can delete inactive accounts after a long time.
- Keep an independent backup of what matters, because sync is not a backup.
Common mistakes
✖ Instead of: Thinking that files in the cloud cannot be lost.
✔ Do this: Providers can fail, accounts can be locked and sync can copy deletions. Keep a separate backup of important files.
✖ Instead of: Closing the laptop while the sync icon shows that it is still syncing.
✔ Do this: Wait until the icon shows that everything is up to date, especially before travelling.
✖ Instead of: Sharing a folder with a link that anyone can open.
✔ Do this: Share with named people where possible, and check the link settings afterwards.
✖ Instead of: Editing the same file in two places at once.
✔ Do this: Edit in one place and let it sync before you open it elsewhere, or use a shared document made for editing together.
If something goes wrong
- My files are not syncing.
- Check that you are online, that the sync program is running and signed in, and that the account's storage is not full. Look at the status icon for a message, then restart the sync program or the laptop.
- A message says that storage is full.
- Open the provider's storage page, find the largest files, delete what you do not need, empty the bin, or move files to a drive. Check whether your email shares the same quota.
- I deleted a file from the cloud folder by mistake.
- Open the bin or trash, on the provider's website or on the computer, and restore it. If it is not there, try version history, then your separate backup.
- A file I need is online only and I have no internet.
- You cannot open it until you reconnect. Next time, mark important files as available on this device before you travel.
Key terms
- Cloud storage
- Online space where a company keeps your files so you can reach them from any device.
- Sync
- Keeping the same files up to date on more than one device or place.
- local copy
- A local copy is a file stored on your own device, as opposed to one that exists only online.
- offline access
- Offline access means being able to open a file or app without an internet connection, because a copy is stored on the device.
- sync conflict
- A sync conflict happens when the same file is changed in two places before they could sync, so the service keeps both versions.
- storage quota
- A storage quota is the amount of space that a cloud service lets your account use.
Practise it for real
Reading is not the same as being able to do it. Complete these on your own computer, then tick only what you have actually done. These ticks are your own honest record: nothing checks them for you.
Find your sync status and a version
If you have a cloud account, open its folder in Files (Ubuntu, where supported) or File Explorer (Windows). Find one small test file you made, for example practice-note.txt. Change it and wait for the sync to finish. Then open the provider's website, find the file, and look for the version history or previous versions option. If you do not have a cloud account yet, skip the website part and write down what you would check.
Plan where your files live
On paper, list ten types of file you own (for example photographs, CV, bank statements, school work, music). For each one, decide where it should live: laptop only, laptop plus cloud, or laptop plus cloud plus a separate backup drive. Mark any file that is too sensitive to put in a shared folder, and say how you will protect it.
Knowledge check
6 questions. You need 80% to pass. Mistakes here are part of learning, and you can retry as often as you like.
Summary
- The cloud is the provider's computers; your files are stored there, not in the sky.
- Sync keeps folders matching, and copies deletions and mistakes too.
- Sync is not a backup: keep a separate copy of important files.
- Mark files as available offline before a journey and wait for syncing to finish.
- Protect the account with a unique passphrase and multifactor authentication.
Checklist: can you do these?
Marking a lesson as read does not prove you can do it. Skills count as demonstrated when you pass the quiz (not yet) and complete the practical tasks (not yet).
Related lessons
References and further reading
Official sources for details that can change between versions.
- OneDrive support (Microsoft)
- Ubuntu Desktop guide: online accounts (Ubuntu)