Cloud Computing Terminology Every Beginner Should Learn

LAYER              IaaS        PaaS        SaaS
Application        You         You         Provider
Data               You         You         You (your content)
Runtime            You         Provider    Provider
Operating system   You         Provider    Provider
Virtual servers    Provider    Provider    Provider
Physical hardware  Provider    Provider    Provider

#!/usr/bin/env bash
# Configure the AWS CLI and run read-only commands (your practice account)
aws configure                      # access key, region (e.g. ap-south-1)
aws sts get-caller-identity        # who am I?
aws ec2 describe-regions --output table | head -15
aws ec2 describe-availability-zones --region ap-south-1 \
  --query 'AvailabilityZones[].ZoneName' --output text

import ipaddress

vpc = ipaddress.ip_network("10.0.0.0/16")
print("VPC addresses:", vpc.num_addresses)

subnets = list(vpc.subnets(new_prefix=24))[:4]
for name, net in zip(["public-a", "public-b", "private-a", "private-b"], subnets):
    print(f"{name:10} {net}  ({net.num_addresses} addresses)")

resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
  tags       = { Name = "learning-vpc" }
}

resource "aws_subnet" "public_a" {
  vpc_id                  = aws_vpc.main.id
  cidr_block              = "10.0.0.0/24"
  availability_zone       = "ap-south-1a"
  map_public_ip_on_launch = true
}

resource "aws_subnet" "private_a" {
  vpc_id            = aws_vpc.main.id
  cidr_block        = "10.0.2.0/24"
  availability_zone = "ap-south-1a"
}

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": ["s3:GetObject"],
      "Resource": "arn:aws:s3:::learning-reports-bucket/*"
    }
  ]
}

# AWS Lambda handler (Python runtime): runs when a file is uploaded to S3
import json

def lambda_handler(event, context):
    records = event.get("Records", [])
    for r in records:
        bucket = r["s3"]["bucket"]["name"]
        key = r["s3"]["object"]["key"]
        print(f"new upload: s3://{bucket}/{key}")
    return {"statusCode": 200, "body": json.dumps({"processed": len(records)})}

# Local test with a fake event:
if __name__ == "__main__":
    fake = {"Records": [{"s3": {"bucket": {"name": "demo"}, "object": {"key": "a.csv"}}}]}
    print(lambda_handler(fake, None))

Term: Availability zone
Plain meaning: A separate group of data centres within a region
Example: Running servers in two zones in the Mumbai region
Why it matters: The app keeps working if one zone fails
Related: Region, high availability, load balancer

Models:     IaaS, PaaS, SaaS, shared responsibility
Infra:      region, availability zone, VPC, subnet, security group
Security:   IAM, role, policy, encryption, MFA
Scale/cost: load balancer, autoscaling, serverless, pay as you go,
            reserved capacity, billing alarm, tagging

Explain each in one sentence, without notes:

1. IaaS vs PaaS vs SaaS
2. Region vs availability zone
3. Public vs private subnet
4. IAM role vs IAM user
5. Why autoscaling saves money
6. What the shared responsibility model means