Cloud Computing

Virtualization lets one physical machine run many isolated virtual machines via a hypervisor; type-1 hypervisors run on bare metal for efficiency, while containers offer lighter isolation by sharing the host kernel.

Cloud service models differ in how much the provider manages: IaaS supplies raw infrastructure, PaaS adds a managed runtime, and SaaS delivers complete applications — with the customer’s responsibility shrinking at each step.

Cloud storage comes in object, block and file forms for different access patterns, and cloud databases range from vertically scaled relational systems to horizontally sharded NoSQL stores, with the CAP theorem framing their consistency trade-offs.

Scalability handles growing load by scaling up (bigger machines) or out (more machines); a load balancer distributes requests across instances, and auto-scaling adjusts instance count automatically to match demand.

Cloud security rests on identity and access management with least privilege, encryption of data at rest and in transit, and network isolation via VPCs and security groups, all under the shared-responsibility model.