Introduction to AWS
Your entry point to the world's most widely used cloud platform.
Amazon Web Services (AWS) is the largest cloud platform in the world. Instead of buying and racking physical servers, you rent computing power, storage, and networking on demand — and pay only for what you use. Most modern DevOps roles expect you to be comfortable in at least one cloud, and AWS is the most common.
🎯 Learning Objectives
By the end of this lesson you will:
- Understand what cloud computing is
- Know what AWS provides
- Understand Regions and Availability Zones
- Understand the shared responsibility model
What is Cloud Computing?
Cloud computing is renting IT resources over the internet instead of owning them.
| Traditional (on-prem) | Cloud (AWS) |
|---|---|
| Buy physical servers | Rent virtual servers in minutes |
| Pay upfront for hardware | Pay only for what you use |
| Weeks to add capacity | Scale up/down in seconds |
| You maintain everything | AWS maintains the hardware |
💡 The mental model
Think of AWS like electricity: you don’t build a power station, you just plug in and pay for what you consume. AWS is computing power on tap.
What Does AWS Offer?
AWS has 200+ services. As a DevOps engineer you’ll start with a core handful:
| Service | Purpose |
|---|---|
| EC2 | Virtual servers |
| S3 | Object storage (files, backups, static sites) |
| IAM | Users, roles, and permissions |
| VPC | Private networking |
| RDS | Managed databases |
Regions and Availability Zones
- A Region is a geographic area (e.g.
us-east-1in Virginia,eu-west-1in Ireland). You choose regions close to your users, or where costs/laws suit you. - Each Region contains multiple Availability Zones (AZs) — physically separate data centres. Spreading your app across AZs means one data-centre failure won’t take you down.
Region: eu-west-1 (Ireland)
├── AZ eu-west-1a (data centre)
├── AZ eu-west-1b (data centre)
└── AZ eu-west-1c (data centre)The Shared Responsibility Model
Security in AWS is shared:
- AWS secures the cloud itself — hardware, data centres, and the underlying infrastructure (“security of the cloud”).
- You secure what you put in the cloud — your data, access permissions, and configuration (“security in the cloud”).
⚠ Most breaches are the customer's side
The majority of cloud security incidents come from misconfiguration — a public S3 bucket, an over-permissive IAM policy — not from AWS being hacked. Getting IAM right (next lesson) is one of your most important jobs.
🧪 Hands-on
Explore the AWS Free Tier
You don’t need to spend money to start learning AWS.
- Create a free AWS account at aws.amazon.com (the Free Tier covers a lot).
- In the console, open the Region selector (top-right) and note the region names.
- Search for the EC2, S3, and IAM services and open each dashboard.
- Set a billing alarm so you’re notified if you ever approach a cost.
🧠 Knowledge Check
What is an AWS Availability Zone?
Under the shared responsibility model, who is responsible for a misconfigured, publicly-exposed S3 bucket?
💼 Interview Preparation
Explain the difference between a Region and an Availability Zone, and why it matters for reliability.
Summary
You now understand what cloud computing and AWS are, how Regions and Availability Zones provide reliability, and how security responsibility is shared. Next, we lock down access with IAM.