"The cloud" is one of those terms that sounds mysterious but is actually simple. When someone says your files are "in the cloud," it means they are stored on someone else's computer – specifically, on large servers owned by companies like Apple, Google, or Microsoft. These servers sit in massive buildings called data centers, and your files are saved there so you can access them from any device with an internet connection.

That is really all it is. The cloud is not floating in the sky. It is just other people's computers, connected to yours through the internet.

Why the cloud exists

Before cloud storage, your files lived only on the device you created them on. If your computer broke or was stolen, those files were gone. If you wanted to share a document, you had to email it or put it on a USB drive.

Cloud storage solves both problems. Your files are automatically copied to a remote server, so they survive even if your device does not. And because they are online, you can get to them from your phone, tablet, another computer, or even a web browser on a friend's machine.

The major cloud services

There are several popular cloud storage services. They all do roughly the same thing, but each one is tied to a different ecosystem:

• iCloud – made by Apple. Built into every iPhone, iPad, and Mac. Stores photos, documents, backups, and app data. Works best if all your devices are Apple
• Google Drive – made by Google. Built into Android phones and Chromebooks. Also accessible from any web browser. Includes Google Docs, Sheets, and Slides
• OneDrive – made by Microsoft. Built into Windows and comes with Microsoft 365 (Word, Excel, PowerPoint). Works well if you use Windows and Office
• Dropbox – an independent service that works on any device or operating system. Popular for sharing files with other people

You are probably already using at least one of these, even if you did not realize it. If you have an iPhone, your photos are likely backing up to iCloud. If you use Gmail, you have Google Drive.

Where are my files: local vs cloud vs both

This is the part that confuses most people. Your files can be in three places:

• Local only – the file exists on your device and nowhere else. If the device breaks, the file is gone
• Cloud only – the file is stored on the remote server but not downloaded to your device. You need an internet connection to open it
• Both (synced) – the file exists on your device and on the cloud server. Changes you make are automatically updated in both places. This is the most common setup

When a service says it "syncs" your files, it means it keeps the local copy and the cloud copy identical. Edit a document on your laptop, and the change appears on your phone automatically, and vice versa.

Sync vs backup: an important difference

These two words sound similar but mean very different things:

Sync keeps files identical across devices. If you delete a file on one device, it gets deleted everywhere (including the cloud). Sync is not protection against accidental deletion – it is about convenience and access.

Backup creates a separate copy of your files that does not change when you change the originals. If you accidentally delete something, the backup still has it. Time Machine on Mac and Windows Backup are backup tools. iCloud, Google Drive, and OneDrive are mostly sync tools (though some offer backup features too).

The safest approach is to use both: sync for everyday convenience, and a separate backup for protection. See the backup your computer guide for more on this.

Storage limits and plans

Every cloud service gives you some free storage, then charges a monthly fee for more:

• iCloud – 5 GB free. Paid plans start at about 50 GB
• Google Drive – 15 GB free (shared with Gmail and Google Photos). Paid plans through Google One
• OneDrive – 5 GB free. 1 TB included with a Microsoft 365 subscription
• Dropbox – 2 GB free. Paid plans start at about 2 TB

If you get a warning that your storage is full, it usually means you need to either delete files you no longer need or upgrade to a paid plan. Photos and videos tend to eat up space the fastest.

Sharing files from the cloud

One of the most useful features of cloud storage is sharing. Instead of emailing a large file (which often fails or compresses the quality), you can send someone a link to the file in your cloud storage. They click the link and can view or download it.

In most cloud services, right-click a file and look for Share or Get link. You can usually choose whether the other person can only view the file or also edit it.

Offline access

Even though cloud files are stored on the internet, you can usually mark specific files to be available offline. This means the service downloads a copy to your device so you can open it without an internet connection. Any changes you make while offline get synced back to the cloud the next time you connect.

Look for an option like Make available offline or Always keep on this device in your cloud app's settings or when you right-click a file.

Is the cloud safe?

Cloud services use strong encryption and security measures to protect your files. For most people, your files are safer in the cloud than on your local device, because cloud providers have teams of security engineers, automatic backups across multiple locations, and protections against hardware failure.

That said, the security of your cloud account depends on your password. Use a strong, unique password and enable two-factor authentication to keep your account secure.

short

• The cloud = your files stored on remote servers (Apple, Google, Microsoft) accessible from any device via the internet
• Sync = keeps files identical across all your devices; deleting on one deletes everywhere
• Backup = a separate copy that does not change when you delete the original
• Free storage: iCloud 5 GB, Google Drive 15 GB, OneDrive 5 GB, Dropbox 2 GB
• Sharing: right-click a cloud file and choose Share or Get link to send it to someone
• Offline access: most services let you mark files to download for use without internet