Deployment Models: Public, Private, Hybrid

Public cloud means the infrastructure (physical servers, storage) is owned and operated by a third-party provider (AWS, Azure, GCP) and shared — via strong virtualization isolation — among many different customers. This is what most people mean by 'the cloud,' and it's what AWS, in the vast majority of cases, provides: you get isolated virtual resources on shared physical hardware, at a much lower cost than dedicated hardware because that hardware is utilized by many customers over time.

Private cloud means infrastructure dedicated entirely to one organization — either physically on their own premises or hosted by a provider but not shared with anyone else. Some regulated industries (banking, government, healthcare) require or strongly prefer this for compliance reasons. AWS offers a 'dedicated' option (Dedicated Hosts, Dedicated Instances) for customers who need physical or licensing isolation while still using AWS's platform.

Hybrid cloud combines both: some workloads stay on-premises or in a private cloud (often for compliance, latency, or legacy-system reasons) while others run in the public cloud, connected together. AWS's hybrid offerings include AWS Direct Connect (a dedicated network link from your data center to AWS) and AWS Outposts (actual AWS hardware installed in your own data center, managed the same way as AWS's cloud infrastructure).