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What is Cloud Computing?
Renting someone else's computer
Cloud computing means using someone else's servers over the internet instead of buying and running your own hardware. When you deploy an app "to the cloud," you are really renting compute, storage and networking from a company like Amazon (AWS), Microsoft (Azure) or Google (GCP), by the hour or by usage.
Why this matters for your career
Almost every Sri Lankan tech job posting now mentions AWS, Azure or GCP. Companies stopped buying physical servers years ago because the cloud is:
- Elastic: you can add or remove capacity in minutes, not weeks
- Pay-as-you-go: you are billed for what you use, not for hardware sitting idle
- Global: your app can run close to users anywhere in the world
The three service models
| Model | You manage | Provider manages | Example |
|---|---|---|---|
| IaaS | OS, runtime, app | Physical hardware, networking | AWS EC2 |
| PaaS | Just your app | OS, runtime, scaling | AWS Elastic Beanstalk |
| SaaS | Nothing | Everything | Gmail, Slack |
This course focuses on IaaS, the layer closest to the metal, and the one that teaches you the most about how systems actually work.
Every lesson from here uses AWS's free tier. You will not need to enter a credit card that gets charged for anything in this course.