Deployment Models: Public, Private, Hybrid
When most people say "the cloud", they mean the big shared providers. But that's not the only shape a cloud can take. Where the computing physically lives — in a shared pool, in a space reserved for one organization, or a mix — has names too, and they come up often.
The four formal deployment models are public, private, community, and hybrid — defined by who the infrastructure is dedicated to. Multi-cloud (using more than one public provider) is a widely-used pattern, but not one of these four formal models. None is complicated once named, and knowing them lets you follow why a bank, a hospital, or a startup each set things up differently.
A simple comparison: public transport is shared, cheap, and ready when you are; a private car is yours alone, fully under your control, but costs more to own and run. Some people use both, depending on the trip. Clouds work the same way.
Public Cloud
The public cloud is the shared providers — AWS, Google Cloud, Azure. You rent a slice of their enormous pool of machines, alongside millions of other customers, each walled off from the others. It's the cheapest and fastest way to get going, with no hardware of your own. This is what the rest of this course mostly means by "the cloud".
Private Cloud
A private cloud is cloud-style infrastructure dedicated to a single organization — running in its own data center, or in a space a provider sets aside just for it. The draw is control: some companies, especially in banking, healthcare, or government, want their systems on hardware no one else touches, often to satisfy strict rules.
Community Cloud
A community cloud is infrastructure shared by a set of organizations that have common requirements — for example, several government agencies that must comply with the same data regulations.
Hybrid and Multi-Cloud
Hybrid means using public and private together — perhaps keeping sensitive data in a private cloud while running the public-facing website in the public cloud. Multi-cloud is a common usage pattern, not one of the four formal models: it means using more than one public provider on purpose — say, AWS for most things and Google Cloud for its data tools. Organizations do this for cost, for specific strengths, or to avoid depending on a single vendor.
- "Private cloud just means more secure." It means single-tenant — dedicated to one organization — not automatically safer. A well-run public cloud is often more secure than a poorly-run private one.
- "Hybrid is a product you buy." It's an architecture choice — a way of using public and private together — not a single service with a price tag.
- "Multi-cloud means everything runs on every cloud at once." Usually it means different workloads live on different providers, each chosen for a reason — not the same thing copied everywhere.
- It explains why a bank or hospital might keep some systems private while a startup goes all-in on the public cloud — the choice reflects real needs, not fashion.
- "Hybrid" and "multi-cloud" are phrases leaders use constantly; knowing what they actually mean keeps you from being lost in strategy conversations.
- It rounds out the foundation: with service models and deployment models in hand, you can place almost any cloud setup you meet on the map.
Knowledge Check
What does "public cloud" mean?
- Renting a slice of a big shared provider's pool, alongside other customers
- A cloud where everyone's data is openly visible to all other users
- Cloud infrastructure built and dedicated entirely to one single organization, not shared with others
- Free computing provided by governments for the general public
A company keeps sensitive data on dedicated private hardware but runs its public website on AWS. What is this called?
- Hybrid — using public and private clouds together
- Multi-cloud — using several public providers at once
- Purely public, since one part happens to run on AWS
- Purely private, since sensitive data is on dedicated hardware
Why is "private cloud means more secure" a misleading idea?
- Private means dedicated to one organization, which isn't the same as being safer
- Because private clouds have consistently been shown to be less secure than well-run public ones
- Because all public clouds expose every customer's data by default
- Because security is only ever a marketing word with no real meaning
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