Cloud computing means using computers that belong to someone else, over the internet, instead of your own. You rent storage, processing power or ready-made software from a provider and pay for what you use, rather than buying and running all the equipment yourself.
How it works
Cloud providers run large buildings full of servers, called data centres, in many places around the world. These servers are shared between many customers. Software divides each machine’s power into smaller portions, so lots of people can use the same hardware at once without seeing each other’s data.
When you use a cloud service, your device sends requests over the internet to those data centres. The work happens there, and the results come back to your screen. Your files might be stored on servers far away, but you see them as if they were on your own device.
Cloud services are often described in three broad groups:
- Software as a service: complete apps you use in a browser or app, such as online email or document editors.
- Platform as a service: ready-made building blocks that developers use to run their own apps without managing servers.
- Infrastructure as a service: raw computing power, storage and networking that a company rents and sets up itself.
Because providers have so many machines, customers can usually get more capacity within minutes when they need it, and give it back when they don’t.
An everyday example
If you save photos from your phone to an online storage service, you are using cloud computing. The photos are copied to the provider’s servers. You can then open them on your laptop, share a link with a friend, or get them back if your phone is lost, because they no longer live on just one device.
Streaming a film works in a similar way. The film isn’t stored on your TV. It sits on servers and is sent to you piece by piece while you watch.
Many office tools work the same way. When several people edit one online document at the same time, the document lives on the provider’s servers, and each person’s changes are sent there and shared with everyone else almost instantly.
Why it matters
Before cloud computing became common, a business that wanted to run a website or an app usually had to buy its own servers, find space for them and keep them running. That cost a lot up front and was hard to scale. If more customers arrived than expected, the system could slow down or crash.
With the cloud, a small team can start with very little and pay more only as it grows. Large companies use it too, because it lets them handle busy periods without keeping extra machines idle for the rest of the year.
For individuals, the cloud is what lets you pick up where you left off on a different device, keep backups without thinking about it, and use powerful apps on a modest phone.
There are trade-offs. You depend on an internet connection and on the provider staying reliable, and your data is stored on someone else’s equipment, so it matters which provider you trust and what its privacy terms say.
Common questions
Is “the cloud” one place?
No. It is a nickname for many data centres run by different companies. Your data is stored on real computers in real buildings, just not ones you can see.
Is cloud storage safe?
Large providers invest heavily in security, but no system is perfect. Using a strong, unique password and turning on two-step sign-in makes a big difference to keeping your own account safe.
What happens if I lose internet access?
Some apps keep a copy on your device so you can keep working offline and sync later. Others won’t work until you are back online.
Related terms
- Server
- Data centre
- API
- Cache
- Backup