AWS for Beginners: Cloud Computing Fundamentals

1Why AWS?

Amazon Web Services has roughly 33% of the cloud infrastructure market — more than Azure and Google Cloud combined. AWS certifications are the most widely recognised in the industry, and the AWS CLI and SDKs are the reference implementation that most cloud tooling builds on.

Learning AWS first gives you transferable cloud fundamentals that apply to other providers, since all major clouds offer equivalent services under different names. The practical reason to start here: the free tier is generous, the documentation is excellent, and the console is a concrete way to learn what "the cloud" actually means.

2The AWS Free Tier and Billing Safety

The AWS free tier comes in two forms, and understanding the difference keeps your learning costs at zero.

• 12-month free tier: services free for your first 12 months after account creation — includes 750 EC2 hours/month (t2.micro or t3.micro), 750 RDS hours/month (db.t2.micro), and 5 GB of S3 storage.
• Always free: services free regardless of account age — includes Lambda (1M requests/month), CloudWatch (10 metrics), and DynamoDB (25 GB).

# Also install and configure the AWS CLI
pip install awscli
aws configure
# Enter: Access Key ID, Secret Access Key, region (e.g. ap-south-1 for India)
aws s3 ls  # list your S3 buckets

3IAM: Identity and Access Management

IAM controls who can do what in your AWS account, built on three core concepts.

IAM best practices: never use the root account for daily work — create an admin IAM user instead. Apply the principle of least privilege, granting only the permissions needed. Use roles for EC2 and Lambda to access other services, and never hardcode credentials.

• Users: individual identities (people or applications) with permanent credentials.
• Roles: temporary identities assumed by services or external users. An EC2 instance assumes a role to access S3 without embedding credentials in code.
• Policies: JSON documents defining what actions are allowed on which resources.

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

4S3: Object Storage

S3 (Simple Storage Service) stores any file (object) in a bucket. Objects can range from 1 byte to 5 TB, and S3 is infinitely scalable, offers 11 nines of durability, and is integral to almost every AWS architecture.

S3 is used for static website hosting, storing user uploads in web apps, data lakes (raw data for analytics), application logs, and backups.

import boto3
s3 = boto3.client("s3")
# Create a bucket
s3.create_bucket(
    Bucket="my-skillveris-data",
    CreateBucketConfiguration={"LocationConstraint": "ap-south-1"}
)
# Upload a file
s3.upload_file("report.pdf", "my-skillveris-data", "reports/2026/report.pdf")
# Download a file
s3.download_file("my-skillveris-data", "reports/2026/report.pdf", "local_report.pdf")
# List objects
response = s3.list_objects_v2(Bucket="my-skillveris-data", Prefix="reports/")
for obj in response.get("Contents", []):
    print(obj["Key"], obj["Size"])

5EC2: Virtual Servers

EC2 (Elastic Compute Cloud) provides virtual machines (called instances) in the cloud. You choose the operating system, CPU, RAM, and storage, and pay per hour. Instance families are tuned for different workloads.

• t2.micro / t3.micro — Low-traffic web apps, learning — Free tier: yes (750 hrs/month)
• t3.medium — Medium web apps — Free tier: no
• c5 / c6 series — CPU-intensive compute — Free tier: no
• r5 / r6 series — Memory-intensive (databases) — Free tier: no
• g4 / p3 series — GPU (ML training) — Free tier: no

# AWS CLI: launch a t3.micro instance
aws ec2 run-instances --image-id ami-0f5ee92e2d63afc18 --instance-type t3.micro --key-name my-keypair --security-group-ids sg-xxxxxxxx --count 1
# Connect via SSH
ssh -i my-keypair.pem ubuntu@ec2-xx-xx-xx-xx.compute.amazonaws.com
# ALWAYS stop (not terminate) instances when not in use
aws ec2 stop-instances --instance-ids i-xxxxxxxxxxxxxxxxx

6Security Groups: Your Firewall

Security Groups are stateful firewalls attached to EC2 instances. They control inbound and outbound traffic by port, protocol, and source.

• SSH access — TCP — Port 22 — Your IP only (not 0.0.0.0/0)
• HTTP web server — TCP — Port 80 — 0.0.0.0/0 (public)
• HTTPS web server — TCP — Port 443 — 0.0.0.0/0 (public)
• Node.js app — TCP — Port 3000 — Load balancer SG only
• PostgreSQL — TCP — Port 5432 — App server SG only

7VPC: Your Private Network

A Virtual Private Cloud (VPC) is your isolated network within AWS. By default, AWS creates a default VPC in each region; for production, create a custom VPC with public and private subnets and the right gateways.

The classic 3-tier architecture: internet → load balancer (public subnet) → EC2 app servers (private subnet) → RDS database (private subnet). The database is never directly exposed to the internet.

• Public subnets: resources that need internet access (load balancers, bastion hosts).
• Private subnets: resources that should NOT be internet-accessible (databases, app servers behind a load balancer).
• Internet Gateway: enables public subnets to reach the internet.
• NAT Gateway: lets private subnet resources initiate outbound internet connections (software updates) without being directly accessible.

8RDS: Managed Databases

RDS (Relational Database Service) provides managed PostgreSQL, MySQL, MariaDB, Oracle, and SQL Server databases. AWS handles backups, patching, failover, and scaling.

RDS best practices: place the database in a private subnet (never expose port 5432 to the internet), use AWS Secrets Manager for credentials, enable automated backups with 7–30 day retention, and use Multi-AZ for production databases.

# Connect to RDS PostgreSQL from Python
import psycopg2
conn = psycopg2.connect(
    host="my-db.xxxxxxxxxxxx.ap-south-1.rds.amazonaws.com",
    port=5432,
    database="mydb",
    user="admin",
    password="from-secrets-manager"  # never hardcode; use AWS Secrets Manager
)

9Lambda: Serverless Functions

Lambda runs code without managing servers. You upload a function, define what triggers it (an HTTP request, an S3 upload, a scheduled time), and AWS scales it automatically — from 0 to thousands of concurrent executions.

Lambda is ideal for API backends (API Gateway + Lambda), processing S3 uploads, scheduled tasks, and event-driven automation. The free tier provides 1 million requests/month and 400,000 GB-seconds of compute — more than enough for side projects.

# Lambda function: triggered by API Gateway HTTP request
import json
def lambda_handler(event, context):
    name = event.get("queryStringParameters", {}).get("name", "World")
    return {
        "statusCode": 200,
        "headers": {"Content-Type": "application/json"},
        "body": json.dumps({"message": f"Hello, {name}!"})
    }

10CloudWatch: Logs and Monitoring

CloudWatch provides centralized logs from all AWS services, metrics dashboards, alarms that trigger when metrics exceed thresholds (CPU > 80%, error rate > 1%), and automated actions in response to those alarms.

# View EC2 or Lambda logs in Python
import boto3
logs = boto3.client("logs")
response = logs.get_log_events(
    logGroupName="/aws/lambda/my-function",
    logStreamName="2026/06/22/[$LATEST]abc123",
    limit=50
)
for event in response["events"]:
    print(event["message"])

11Deploying a Web App on EC2

Once you've SSH-ed into an EC2 instance, deploying a web app means installing dependencies, cloning your code, running it with a production server, and putting Nginx in front as a reverse proxy.

# After SSH-ing into your EC2 instance (Ubuntu 22.04)
# Install dependencies
sudo apt update && sudo apt install -y python3-pip nginx
# Clone your app
git clone https://github.com/yourname/your-app.git
cd your-app
pip3 install -r requirements.txt
# Run with gunicorn (production WSGI server)
pip3 install gunicorn
gunicorn -w 4 -b 127.0.0.1:8000 main:app &
# Configure Nginx as reverse proxy
# /etc/nginx/sites-available/your-app:
# server {
#   listen 80;
#   location / { proxy_pass http://127.0.0.1:8000; }
# }
sudo nginx -t && sudo systemctl restart nginx

12Key Takeaways

These habits keep your AWS learning safe, secure, and cost-controlled.

• Set up billing alerts before anything else; the free tier is generous but easy to accidentally exceed.
• IAM: use the principle of least privilege; use roles for services, never hardcode credentials.
• S3 for files; EC2 for servers; RDS for databases; Lambda for serverless functions.
• Databases go in private subnets; never expose port 5432/3306 to the internet.
• Always stop (not terminate) EC2 instances and RDS databases when not in use.

13What to Learn Next

Continue your cloud journey beyond the core services.

• Docker for Beginners — containerise your apps before deploying to EC2 or ECS.
• Kubernetes Explained — orchestrate containers at scale with EKS.
• AWS Certification Guide — Cloud Practitioner then Solutions Architect Associate.

14Frequently Asked Questions

Is AWS the same as the cloud? No. "The cloud" refers to remotely hosted computing infrastructure. AWS is the largest cloud provider, but Azure (Microsoft), GCP (Google), and others also provide cloud infrastructure. The concepts (virtual machines, managed databases, object storage, serverless) are the same across providers; the service names differ.

What region should I use? For learners in India, ap-south-1 (Mumbai) gives the lowest latency. For production apps serving global users, consider multi-region. Not all services are available in all regions — check the AWS regional services list for anything specific.

Is EC2 or Lambda better for a web app? Lambda + API Gateway is simpler to deploy and scales to zero (no cost when idle), making it ideal for low-traffic or intermittent workloads. EC2 gives you full control and is more predictable for sustained traffic. For a new project, start with Lambda; migrate to EC2 or ECS if you hit Lambda limitations (15-minute timeout, cold starts, container size).

How do I avoid accidental AWS bills? Four habits: set billing alerts at $5 and $10 before you start; stop EC2 and RDS instances when not in use; delete resources you're not actively using; and review the billing dashboard weekly until you understand your usage pattern. Lambda, S3 (under 5GB), and DynamoDB (under 25GB) have genuinely free always-on tiers.