1.1 What Is Cloud Computing?

Quick Answer: Cloud computing is the on-demand delivery of compute power, database storage, applications, and other IT resources over the internet with pay-as-you-go pricing. Instead of buying, owning, and maintaining physical data centers and servers, you access technology services on an as-needed basis from a provider like AWS.

The NIST Definition

The National Institute of Standards and Technology (NIST) defines cloud computing through five essential characteristics:

Traditional IT vs. Cloud Computing

Understanding the shift from traditional, on-premises IT to the cloud is essential for the exam.

Traditional (On-Premises) IT

• Buy hardware upfront (servers, storage, networking)
• Build and staff your own data center
• Estimate capacity months or years in advance — and risk guessing wrong
• Maintain everything: hardware, cooling, power, physical security
• Capital expenditure (CapEx): large upfront investment
• Slow provisioning: weeks or months to stand up new servers

Cloud Computing (AWS)

• Rent resources on demand — no upfront hardware purchases
• AWS manages the data centers, hardware, and infrastructure
• Scale dynamically — add or remove resources in minutes
• Pay only for what you use (metered billing)
• Operating expenditure (OpEx): variable cost based on consumption
• Fast provisioning: launch new servers in seconds

On the Exam: Expect questions comparing traditional IT with the cloud. The six advantages below are the canonical AWS answer set — memorize them.

The Six Advantages of Cloud Computing

AWS articulates six advantages that appear frequently on the exam:

1. Trade fixed expense for variable expense. Pay only when you consume resources and only for how much you consume, instead of investing heavily before you know how you will use it.
2. Benefit from massive economies of scale. Aggregated usage from hundreds of thousands of customers lets AWS achieve lower pay-as-you-go prices.
3. Stop guessing capacity. Access as much or as little as you need and scale up or down with a few minutes' notice — no more over- or under-provisioning.
4. Increase speed and agility. New resources are a click away, cutting the time to provision from weeks to minutes.
5. Stop spending money running and maintaining data centers. Focus on projects that differentiate your business, not the undifferentiated heavy lifting of racking, stacking, and powering servers.
6. Go global in minutes. Deploy to multiple Regions worldwide with a few clicks for lower latency and a better customer experience.

AWS Global Infrastructure

AWS operates one of the largest cloud infrastructures in the world. The numbers grow regularly, so treat these as approximate minimums:

Regions

A Region is a separate geographic area (for example, us-east-1 in Northern Virginia or eu-west-1 in Ireland). Each Region is independent, and your data does not leave a Region unless you explicitly move it — critical for data sovereignty and compliance. Each AWS Region is built from a minimum of three physically separated Availability Zones.

How to choose a Region:

• Compliance / data governance: some data must remain in a specific country
• Latency: choose the Region closest to your users
• Service availability: not every service launches in every Region
• Pricing: costs vary by Region

Availability Zones

Each Region contains multiple Availability Zones (AZs). An AZ is one or more discrete data centers with redundant power, networking, and connectivity. AZs in a Region are interconnected by high-bandwidth, low-latency links yet are physically separated (often many kilometers apart) so a flood, fire, or power loss in one AZ does not take down another. Deploying across multiple AZs is the foundation of high availability on AWS.

Edge Locations

Edge locations are sites used by Amazon CloudFront (the CDN) and other edge services to cache content close to end users for lower latency. There are far more edge locations than Regions or AZs, putting content within a short network hop of most users worldwide.

Local Zones, Wavelength, and Outposts

Beyond Regions and AZs, AWS extends infrastructure closer to users for specialized needs. Local Zones place compute, storage, and select services in large metro areas to deliver single-digit-millisecond latency for use cases like media rendering or real-time gaming. Wavelength Zones embed AWS infrastructure inside telecom carriers' 5G networks for ultra-low-latency mobile and edge applications. AWS Outposts brings AWS hardware into your own data center for hybrid or low-latency on-premises needs.

For the exam, you do not need deep detail — just recognize each as a way AWS pushes its global infrastructure nearer to where data is produced and consumed.