In a public cloud, the infrastructure belongs to a large company and many customers use it at the same time. Each customer has their own resources and is isolated from the others, but the underlying hardware is shared. Access is through the internet, usually with a console or an API.
Main features#
- Pay per use: you pay for what you actually use.
- Fast scaling: you add dozens of servers in minutes.
- No hardware upkeep: a disk failure or a data center power cut isn't your concern.
- Geographic reach: you can run your service in several regions.
Example#
A news site whose traffic multiplies on days of big events uses a public cloud so it buys extra capacity only on those days and then releases it.
Versus a private cloud#
A private cloud is dedicated to a single organization and gives more control, but costs more and takes more effort to manage. Many organizations use a mix of both, which is called a hybrid cloud.
Important notes#
"Public" means the infrastructure ownership is shared, not that your data is visible to everyone. But you must configure access correctly. Availability of some providers also varies by country because of regulations, so check which providers and regions you are allowed to use.