What makes something cloud computing
Cloud computing delivers IT resources over the internet on a pay-as-you-go basis. The National Institute of Standards and Technology (NIST) defines five essential characteristics: on-demand self-service (you provision without calling anyone), broad network access (accessible from any device with internet), resource pooling (AWS infrastructure is shared across many customers), rapid elasticity (capacity scales up or down quickly), and measured service (you pay only for what you use).
The three deployment models describe where the infrastructure runs. Public cloud means the infrastructure is owned and operated by AWS and shared among customers. Private cloud means resources run in a dedicated environment controlled by one organization, often on-premises. Hybrid cloud connects on-premises infrastructure to public cloud services, which is the most common real-world architecture for enterprises migrating gradually.
AWS publishes six advantages of cloud computing that the exam tests directly: trade capital expense for variable expense, benefit from massive economies of scale, stop guessing capacity, increase speed and agility, stop spending money running and maintaining data centers, and go global in minutes. Each advantage maps to a concrete cost or operational benefit compared to traditional data center ownership.
Cloud economics and the AWS global infrastructure
The shift from capital expense (CapEx) to operational expense (OpEx) is the headline economics argument for cloud. Buying servers means paying for maximum capacity upfront, then owning hardware that sits idle most of the time. AWS charges only for what you actually consume, turning a large fixed cost into a smaller variable cost that scales with your actual workload.
AWS infrastructure is organized into Regions and Availability Zones. A Region is a geographic area containing multiple isolated datacenters. An Availability Zone (AZ) is one or more datacenters within a Region with independent power, cooling, and networking. Resources deployed across multiple AZs survive the failure of any single facility. Edge locations are smaller points of presence used by CloudFront and Route 53 to serve content closer to end users, separate from Regions and AZs.
Choosing a Region involves four considerations: compliance and data residency requirements (some industries must keep data in specific countries), latency to your end users (closer is faster), service availability (not all AWS services launch in every Region simultaneously), and pricing (per-Region rates vary).
How to choose the correct answer
Five NIST cloud characteristics: on-demand self-service, broad network access, resource pooling, rapid elasticity, measured service. Know all five.
Six AWS advantages: trade CapEx for OpEx, economies of scale, stop guessing capacity, speed and agility, stop running data centers, go global in minutes.
Deployment models: public cloud (AWS-owned, shared), private cloud (dedicated, often on-premises), hybrid (connected on-premises to cloud).
Region: geographic area with multiple AZs. AZ: isolated datacenter(s) within a Region. Edge location: CloudFront/Route 53 caching point.
Region selection factors: compliance, latency, service availability, pricing. Compliance always overrides the others when it applies.