Introduction to Cloud Computing and AWS
# CHAPTER 1
Introduction to Cloud Computing and AWS
Before cloud computing, launching a web application meant buying a server.
Not renting capacity — buying hardware. You estimated your peak traffic, purchased a machine sized for it, waited weeks for delivery, installed it in a rack, and then owned that capacity permanently. Guess too low and the site fell over on your best day. Guess too high, which everyone did, and you had paid for hardware that idled at eight percent utilisation for three years. Either way the money was spent before the first user arrived.
Cloud computing changes the shape of that decision rather than merely the price. Capacity becomes something you request in seconds and stop paying for the moment you release it. A server that costs a few cents an hour can be created for an experiment and destroyed the same afternoon. Capital expenditure becomes operating expenditure, and — more importantly for a small team — the cost of being wrong drops to almost nothing.
AWS was first to market in 2006 and remains the largest provider, offering somewhere north of two hundred services. That breadth is genuinely intimidating and mostly irrelevant to you: a working knowledge of compute, storage, networking and identity covers the overwhelming majority of real usage.
One warning worth taking seriously from the outset. AWS bills for what is running, not what you are using, and an instance left on by accident bills continuously. Set a billing alarm before you launch anything — this chapter shows you how, alongside creating your account and understanding the shared responsibility model.
1. Beginner-Friendly Explanation
Imagine generating electricity.- On-Premises (The old way): You build a coal power plant in your backyard to power your house. It costs millions of dollars, takes years to build, and if it breaks, your house goes dark. You also pay for it even when you aren't using electricity.
- Cloud Computing (The new way): You plug your TV into the wall. A massive power company (AWS) generates the electricity miles away. You only pay for the exact watts of electricity you use. If you need more, you plug in another TV. If you go on vacation, you unplug it and pay nothing.
Cloud Computing is simply renting someone else's computers, storage, and databases over the internet, and paying only for what you use.
2. Types of Cloud Computing (The Service Models)
Cloud services are divided into three tiers:- 1. IaaS (Infrastructure as a Service): AWS provides the raw hardware (Servers, Hard Drives). You manage the Operating System and everything else. (Example: AWS EC2).
- 2. PaaS (Platform as a Service): AWS manages the hardware AND the Operating System. You just bring your application code. (Example: AWS Elastic Beanstalk).
- 3. SaaS (Software as a Service): A completed software product you just use. (Example: Gmail, Netflix, Zoom).
3. Public vs Private Cloud
- Public Cloud: AWS, Azure, Google Cloud. Anyone with a credit card can rent space. Hardware is shared among millions of customers securely.
- Private Cloud: A company (like a highly secure bank) builds its own cloud infrastructure in its own private building, used only by its employees.
- Hybrid Cloud: A mix of both. The bank keeps highly sensitive data in a Private Cloud but uses the Public Cloud for its public-facing website.
4. AWS Global Infrastructure
AWS does not have just one building. It has a massive global network.Regions:
A Region is a physical geographical location in the world (e.g., us-east-1 in N. Virginia, or eu-west-2 in London). When you launch a server, you must choose a Region.
*Tip:* Always choose the Region closest to your customers to reduce lag (latency).
Availability Zones (AZs): Inside every Region, there are multiple (usually 3 or more) Availability Zones. An AZ is a distinct, heavily guarded data center building. *Why?* If a flood destroys Availability Zone A in London, your application automatically shifts to Availability Zone B a few miles away, so your website never goes offline.
5. AWS Pricing Basics
AWS operates on a Pay-As-You-Go model.- You pay for *Compute* (how long a server is turned on, billed by the second).
- You pay for *Storage* (how many Gigabytes of data you store).
- You pay for *Data Transfer OUT* (data leaving AWS to the internet).
- *Data Transfer IN* (uploading to AWS) is almost always FREE.
6. Mini Project: Create an AWS Account
-
1.
Go to
aws.amazon.com.
- 2. Click Create an AWS Account.
- 3. Follow the prompts (you will need an email, phone number, and a credit/debit card to verify identity).
- 4. Once logged in, you will see the AWS Management Console—your central dashboard for controlling the cloud. Look at the top right corner; you will see your current selected Region!
7. Best Practices
- Region Selection: Do not randomly select Regions. If your company is legally required to keep user data inside Europe (GDPR compliance), you MUST select a European Region (like Frankfurt or Paris).
8. Common Mistakes
- Assuming the Cloud is "Magic": The cloud is just physical computers sitting in large, windowless warehouses. Hardware can still fail. AWS provides the tools (Availability Zones) to survive failures, but *you* are responsible for configuring your app to use those tools.
9. Exercises
- 1. Match the service to the model: Gmail, AWS EC2, AWS Elastic Beanstalk. (Which is IaaS, PaaS, SaaS?)
- 2. Explain why a single AWS Region contains multiple Availability Zones.
10. MCQs with Answers
A startup decides to rent raw virtual servers from AWS to install their own custom Linux operating system. Which cloud computing model does this represent?
What is an AWS Availability Zone (AZ)?
11. Interview Questions
- Q: Explain the difference between an AWS Region and an Availability Zone. How do these concepts relate to high availability and disaster recovery?
- Q: Define Cloud Computing and contrast the Pay-As-You-Go pricing model with traditional On-Premises capital expenditure (CapEx).