How Does Cloud Computing Actually Work? Explained Simply

#!/usr/bin/env bash
# Run inside a cloud VM (or any Linux machine) to see what it is
set -euo pipefail
echo "Virtualisation: $(systemd-detect-virt 2>/dev/null || echo unknown)"
echo "CPUs: $(nproc)"
free -h | awk '/Mem:/ {print "Memory: " $2}'
df -h / | awk 'NR==2 {print "Root disk: " $2}'
uname -sr

Virtual machine:
  hardware -> hypervisor -> guest OS -> your app
  + strong isolation, any OS
  - heavier, slower to start

Container:
  hardware -> host OS -> container runtime -> your app
  + light, starts in seconds
  - shares the host kernel

Cloud services use both, often containers running on VMs.

#!/usr/bin/env bash
# Requires AWS CLI configured with credentials
set -euo pipefail
aws ec2 describe-regions --query 'Regions[].RegionName' --output table
aws ec2 describe-availability-zones --region ap-south-1 \
  --query 'AvailabilityZones[].ZoneName' --output table

                 On-premises  IaaS      PaaS      SaaS
Application       You          You       You       Provider
Data              You          You       You       Provider*
Runtime           You          You       Provider  Provider
Operating system  You          You       Provider  Provider
Virtualisation    You          Provider  Provider  Provider
Hardware          You          Provider  Provider  Provider

* You still control who can access your data.

#!/usr/bin/env bash
# First lab: create storage, upload a file, then clean up
set -euo pipefail
BUCKET=cloud-basics-$RANDOM
aws s3 mb "s3://$BUCKET" --region ap-south-1
echo "hello cloud" > hello.txt
aws s3 cp hello.txt "s3://$BUCKET/"
aws s3 ls "s3://$BUCKET/"
# Clean up so nothing keeps costing money
aws s3 rb "s3://$BUCKET" --force

# Rough monthly estimate with placeholder prices; use the provider's
# official pricing page or calculator for real numbers.
hourly_vm_price = 0.0   # fill in from the pricing page
storage_gb_price = 0.0  # per GB-month

vm_hours = 8 * 22       # 8 hours a day, 22 working days
storage_gb = 20

cost = vm_hours * hourly_vm_price + storage_gb * storage_gb_price
print(f"VM hours: {vm_hours}, storage: {storage_gb} GB, estimate: {cost:.2f}")

Cloud computing   Renting compute, storage and services over the internet
Data centre       Building with servers, power and cooling
Hypervisor        Software that runs many VMs on one server
VM                Isolated virtual server with its own OS
Container         Lightweight app package sharing the host kernel
Region            Geographic area with data centres
Availability zone Separate data centre(s) within a region
IaaS/PaaS/SaaS    Levels of what the provider manages
Pay-as-you-go     Paying for what you use

Day 1  Create a free-tier account; enable MFA; set a budget alert
Day 2  Explore regions and the console
Day 3  Object storage: create, upload, delete
Day 4  Launch a small VM; connect; inspect it; terminate
Day 5  IAM: create a user with limited permissions
Day 6  Install the CLI and repeat Day 3 with commands
Day 7  Write notes explaining each step in simple words

[ ] MFA on the root or main account
[ ] Budget alert set
[ ] Use a limited IAM user, not root
[ ] Never commit access keys to Git
[ ] Delete or stop resources after each lab
[ ] Check the billing page weekly