By Samuel Andong, Cloud Computing student
When I started my cloud computing course, I kept hearing three terms: IaaS, PaaS and SaaS. This article explains the first one, Infrastructure as a Service, in simple language. It then looks at Amazon EC2 as a real case study.
What is IaaS?
Infrastructure as a Service (IaaS) is a cloud model where a provider rents you computing resources over the internet. These resources are virtual servers, storage, and networking. You do not buy or maintain any physical hardware. You create what you need in minutes, and you pay for what you use.
Think of renting an empty building. The owner looks after the land, the walls, the electricity and the security guards. You decide what goes inside, how to arrange it, and who comes in.
IaaS vs PaaS vs SaaS
The main difference is who manages what.
Model
You manage
The provider manages
Example
IaaS
Operating system, runtime, apps, data
Servers, storage, networking, virtualization
Amazon EC2, Oracle Cloud Infrastructure
PaaS
Your app and data
Everything below the app, including the OS
Cloudflare Workers, Railway
SaaS
Only your own use of it
The whole application
Gmail, Google Docs
IaaS gives you the most control, but also the most responsibility. If you rent a server, you must install updates, secure it and set it up yourself.
Key characteristics of IaaS
• On-demand: you can create or delete a server in minutes.
• Pay as you go: you are billed for usage, not for owning hardware.
• Scalable: you can add more servers when traffic grows and remove them when it drops.
• Full control: you choose the operating system, software and network rules.
• Global: you can place servers in data centers around the world.
Case study: Amazon EC2
Amazon Elastic Compute Cloud (EC2) is the IaaS service from Amazon Web Services (AWS). It lets you rent virtual machines, called instances, and it is one of the best-known IaaS products in the world.
The main building blocks
• Instances: the virtual servers. You pick a type based on CPU, memory and cost. Some are small for tests, and others are large for heavy workloads.
• AMI (Amazon Machine Image): a template that holds the operating system and software. You pick an AMI, such as Ubuntu or Windows, when you launch a server.
• EBS (Elastic Block Store): storage disks that attach to your instance, like a hard drive.
• VPC and security groups: your private network and the firewall rules that decide which traffic can reach your server, for example port 80 for web traffic and port 22 for SSH.
• Key pairs: a secure login method, so you connect with a private key file instead of a password.
• Regions and Availability Zones: AWS has data centers in many parts of the world. You choose where your server runs, and you can spread servers across zones for reliability.
How you pay
EC2 offers several pricing options:
• On-Demand: pay per use with no commitment. This is best for beginners and short projects.
• Reserved or savings plans: commit to a period of usage for a lower price.
• Spot instances: use spare capacity at a large discount, with the risk that AWS may take it back.
AWS has offered a free tier for new accounts. Always check the current terms and set a billing alert so you are not surprised by a bill.
Scaling
Auto Scaling can add EC2 instances when traffic rises and remove them when it falls. A load balancer spreads visitors across the servers. This is how a busy website can survive a sudden spike without crashing.
Comparison: Amazon EC2 vs Oracle Cloud Infrastructure
Oracle Cloud Infrastructure (OCI) is another major IaaS provider. It offers the same core idea as EC2, which is virtual servers, storage and networking on demand, but it uses different names for many things.
Feature
Amazon EC2 (AWS)
Oracle Cloud Infrastructure
Virtual server
Instance
Compute instance
Server sizes
Instance types
Shapes
OS templates
AMI
Images
Disk storage
EBS
Block Volume
Private network
VPC
VCN (Virtual Cloud Network)
Firewall rules
Security groups
Security lists and network security groups
Organizing resources
Accounts and tags
Compartments
Server login
Key pair
SSH key pair
Free option
Free tier for new accounts
Always Free resources and a trial credit
The terms differ, but the workflow is almost the same: pick an image, choose a server size, set the network rules, add an SSH key and launch. Once you understand one IaaS provider, learning another is mostly learning its vocabulary. Free offers and limits change often, so check each provider's current terms before you sign up.
Example: hosting a website on EC2
Here is the typical flow for putting a small website online on IaaS:
- Create an AWS account and choose a region.
- Launch an instance and select an Ubuntu AMI.
- Create a key pair and download the private key.
- Set the security group to allow SSH (port 22) from your own IP and HTTP (port 80) from anywhere.
- Connect with SSH, install a web server such as Nginx, and copy your files to it.
- Open the instance's public address in a browser to see the site. Compare this with a PaaS platform. On a platform like Cloudflare, I connected my GitHub repository and the platform published my site. With IaaS, I would have to create the server, install the web server and secure it myself. That is more work, but it gives me full control. Benefits of IaaS • No upfront hardware cost • Fast setup and easy experimentation • Flexible scaling up and down • Full control of the operating system and software • Reliable infrastructure run by experts Challenges of IaaS • More responsibility: you handle patches, security settings and backups. • Cost surprises: a forgotten running server keeps charging you. • Skills needed: you need to understand servers, networking and security. • Vendor lock-in: moving to another provider can take effort. When should you choose IaaS? Choose IaaS when you need full control, custom software, or special network settings. Choose PaaS when you just want to deploy code quickly, and SaaS when you only need a ready-made tool. Conclusion IaaS is the foundation of cloud computing. It gives you virtual servers, storage and networks on demand, with control over everything above the hardware. Amazon EC2 shows how this works in practice: you choose a server, set up the network, install your software and pay for what you use. For a student, IaaS is a great way to learn how real systems run, as long as you secure your servers and watch your costs. References • AWS documentation: What is Amazon EC2? (docs.aws.amazon.com) • AWS Pricing for EC2 (aws.amazon.com/ec2/pricing) • NIST definition of cloud computing, Special Publication 800-145
