What it is: AWS IAM manages access permissions to AWS resources. It controls who (authentication) can perform what actions (authorization) on specific AWS services.

Key Components:

• IAM Users & Groups: Individuals or teams needing access to the AWS Console or CLI.
• IAM Roles: Temporary security credentials granted to AWS services (e.g. allowing an EC2 instance to read files from S3).
• IAM Policies: JSON document definitions specifying Effect: Allow or Deny for specific API actions.

What it is: Amazon EC2 provides resizable virtual servers (called instances) in the cloud. You have full root/administrator control over the operating system (Ubuntu, Amazon Linux, Windows).

Key Concepts:

• AMI (Amazon Machine Image): Pre-configured template containing OS and software drivers.
• Instance Types: Categorized by CPU/RAM focus (e.g., General Purpose t3.micro, Compute Optimized c6g.large, Memory Optimized r6g.xlarge).
• EBS (Elastic Block Store): High-performance persistent block storage disk attached to EC2 instances.

What it is: Amazon S3 is object storage designed for storing and retrieving any amount of data (images, videos, backups, static websites, logs) from anywhere on the web.

Key Benefits:

• High Durability: Designed for 99.999999999% (11 9s) of data durability across multiple Availability Zones.
• Buckets: Top-level containers with unique global names where objects are stored.
• Security: Supports server-side encryption (SSE-S3, SSE-KMS) and S3 Block Public Access to prevent accidental data leaks.

What it is: AWS VPC lets you provision a logically isolated section of the AWS Cloud where you can launch AWS resources in a virtual network that you define.

Subnet Breakdown:

• Public Subnets: Connected directly to the internet via an Internet Gateway (IGW). Used for web load balancers and public servers.
• Private Subnets: Isolated from the public internet. Used for backend application microservices and databases (RDS). Connects outbound via NAT Gateways.

What it is: A Security Group acts as a stateful virtual firewall for EC2 instances to control inbound and outbound network traffic at the instance level.

Key Characteristics:

• Stateful: If you allow an inbound request on Port 80, the outbound response is automatically allowed.
• Default Deny: All inbound traffic is denied by default until you explicitly add an allow rule (e.g. HTTP 80, HTTPS 443, SSH 22).

What it is: AWS Elastic Load Balancing (ELB) automatically distributes incoming application traffic across multiple EC2 targets, container tasks, or IP addresses to ensure high availability.

Types of Load Balancers:

• Application Load Balancer (ALB): Operates at Layer 7 (HTTP/HTTPS) for path-based routing (`/api`, `/users`).
• Network Load Balancer (NLB): Operates at Layer 4 (TCP/UDP) for ultra-low latency and millions of requests per second.

What it is: AWS Auto Scaling monitors your applications and automatically adjusts compute capacity (scaling EC2 fleets up or down) based on CPU utilization, memory, or custom metrics.

Why it matters: Prevents application crashes during unexpected traffic spikes and saves cloud money during quiet night hours when extra servers aren't needed.

What it is: Amazon RDS makes it easy to set up, operate, and scale relational databases in the cloud (MySQL, PostgreSQL, MariaDB, Oracle, SQL Server, and Amazon Aurora).

Managed Features: AWS automatically handles hardware provisioning, database OS patching, automated daily backups, and Multi-AZ failover replication.

What it is: AWS Lambda allows you to run code without provisioning or managing servers (Serverless). You pay only for the exact milliseconds of compute time consumed when your code executes.

Event-Driven Triggers: Lambda code runs automatically in response to events like an image uploaded to S3, an API call via API Gateway, or a database record change in DynamoDB.

What it is: CloudWatch is a monitoring and management service that collects operational metrics, log files, and sets automated alarms for AWS resources and applications.

Key Features:

• Metrics: Tracks CPU utilization, memory, network latency.
• Logs: Centralized log storage from EC2 instances, Lambda functions, and EKS clusters.
• Alarms: Triggers automated SNS alerts or Auto Scaling actions when thresholds are breached.

What it is: Route 53 is a highly available and scalable Domain Name System (DNS) web service. It connects user requests to infrastructure running in AWS (EC2, S3, ALB).

Advanced Routing Policies: Supports Latency-Based Routing, Geo-Location Routing, Weighted Routing, and Automated DNS Failover based on health checks.

What it is: CloudFront is AWS's global Content Delivery Network (CDN) service that delivers web content, videos, images, and APIs to users with low latency and high transfer speeds via edge locations.

Why it's essential: Instead of a user in Tokyo fetching images from a server in Virginia, CloudFront caches the images at an Edge Location in Tokyo for instant loading.