Cloud Computing Fundamentals

Cloud computing delivers computing resources — servers, storage, databases, networking — over the internet on a pay-as-you-go model. Understanding the service models and deployment options is the foundation for architecting cloud-native systems.

Service Models

Infrastructure as a Service (IaaS) gives raw compute and storage. Platform as a Service (PaaS) adds a managed runtime and middleware layer. Software as a Service (SaaS) delivers complete applications. Each level of abstraction trades control for reduced operational burden.

Shared Responsibility

Cloud providers secure the infrastructure; customers secure what they run on it. The boundary shifts depending on the service model: with IaaS you manage the OS and above, with SaaS you manage only your data and user access.

Choosing a Deployment Model

Public cloud is the default for most workloads — it offers elasticity and global reach with no upfront hardware costs. Private cloud suits regulated industries with strict data sovereignty requirements. Hybrid connects both, often used during cloud migrations.