Day 1 Learning cloud | Cloud Computing Basics — IaaS, PaaS, SaaS and Linux Basics

What is Cloud?

Cloud simply means renting someone else's computer/server over the internet, instead of buying and maintaining your own hardware. Just like you pay for electricity without owning a power plant, you pay a cloud provider (AWS, Azure, Google Cloud) for computing power.

Shared Responsibility Model

In cloud, security and management work is split between two parties:

• Provider (AWS/Azure/GCP) — takes care of data centers, physical hardware, networking, and virtualization security
• User (you) — takes care of your data, your apps, access control, and sometimes OS updates (depends on the model)

The more control you have, the more responsibility you carry. That's why IaaS, PaaS, and SaaS split responsibility differently.

1. IaaS (Infrastructure as a Service)

What you get: Just a virtual machine, storage, and network — basic infrastructure. You install the OS, apply updates, handle security patches — everything yourself.

Example:

• AWS EC2, Google Compute Engine, Azure VM
• You rent an Ubuntu server and install your own software on it

Who needs it: Developers who want full control — custom setup, their own tech stack.

You manage: OS, Runtime, App, Data
Provider manages: Servers, Storage, Networking, Virtualization

2. PaaS (Platform as a Service)

What you get: The OS and infrastructure are already set up. You just deploy your code — the platform handles the rest.

Example:

• Heroku, Google App Engine, AWS Elastic Beanstalk
• You upload your Node.js or Python app, and deployment happens automatically

Who needs it: Developers who want to focus only on coding, without worrying about infrastructure.

You manage: App, Data
Provider manages: OS, Runtime, Servers, Storage, Networking

3. SaaS (Software as a Service)

What you get: A complete, ready-made software product. Just log in and use it.

Example:

• Gmail, Google Docs, Netflix, Zoom, Dropbox
• Nothing to install — open your browser and start working

Who needs it: End users — anyone who just wants to use the product, no coding involved.

You manage: Just your data/settings
Provider manages: Everything else — from app to infrastructure

Quick Comparison

Model	What You Do	Example
IaaS	Manage OS + App yourself	AWS EC2
PaaS	Just deploy your code	Heroku
SaaS	Just use it	Gmail

Pizza analogy (a popular way to explain this):

• IaaS = raw ingredients at home, you make the whole pizza yourself
• PaaS = kitchen is ready, dough is made, you just add toppings
• SaaS = you order a pizza and simply eat it

Linux Basics (Important for Cloud)

Most cloud servers run on Linux, so these commands are essential to know:

pwd                    # show current folder
ls -la                 # list files/folders
cd foldername          # move into a folder
mkdir newfolder        # create a new folder
touch file.txt         # create a new file
cat file.txt           # view file content
sudo apt update        # update package list
sudo apt install nginx # install software
systemctl status nginx # check service status
chmod 755 file.sh      # set file permissions
ssh user@server_ip     # connect to a remote server

Key concepts:

• Root user = admin, can do everything (using sudo)
• File permissions = read (r), write (w), execute (x)
• Package manager = apt (Ubuntu/Debian), yum (CentOS)
• Process management = ps, top, kill

Conclusion

Understanding cloud isn't hard — just remember: the more control you want, the more responsibility you take on. If you're a beginner, start with SaaS. If you're a developer, try PaaS. When you need full control, go for IaaS. Keep practicing Linux basics, since 90% of cloud servers run on it.