Cloud Foundations

Before diving into AWS services, you need to understand the fundamentals of cloud computing and why it matters.

What You'll Learn

#	Topic
1	What is Cloud Computing?
2	IaaS vs PaaS vs SaaS
3	Public vs Private vs Hybrid Cloud
4	Introduction to AWS
5	AWS Global Infrastructure
6	Shared Responsibility Model
7	Well Architected Framework

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1. What is Cloud Computing?

Cloud computing is the on-demand delivery of IT resources over the internet with pay-as-you-go pricing.

Instead of buying, owning, and maintaining physical data centers and servers, you can access technology services (computing power, storage, databases) from a cloud provider like AWS.

Key Characteristics

Characteristic	Description
On-demand self-service	Provision resources without human interaction
Broad network access	Access from anywhere via internet
Resource pooling	Provider's resources shared among customers
Rapid elasticity	Scale up/down instantly based on demand
Measured service	Pay only for what you use

Benefits of Cloud

• No upfront cost — No need to buy expensive hardware
• Pay-as-you-go — Like electricity, pay for what you consume
• Elastic capacity — Scale to millions of users or down to zero
• Speed & agility — Deploy globally in minutes
• No maintenance — Provider handles hardware failures

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2. IaaS vs PaaS vs SaaS

Cloud services are categorized into three models based on what the provider manages vs what you manage.

Service Models Comparison

Model	You Manage	Provider Manages	Examples
IaaS	OS, Runtime, Apps, Data	Hardware, Networking, Virtualization	EC2, VPC, EBS
PaaS	Apps, Data	Everything else	Elastic Beanstalk, Lambda, RDS
SaaS	Just use it	Everything	Gmail, Slack, Salesforce

Visual Stack

┌─────────────────────────────────────────────────────┐
│                    Applications                      │ ← You manage (IaaS)
├─────────────────────────────────────────────────────┤
│                       Data                           │ ← You manage (IaaS, PaaS)
├─────────────────────────────────────────────────────┤
│                      Runtime                         │ ← Provider manages (PaaS)
├─────────────────────────────────────────────────────┤
│                    Middleware                        │ ← Provider manages (PaaS)
├─────────────────────────────────────────────────────┤
│                   Operating System                   │ ← Provider manages (PaaS)
├─────────────────────────────────────────────────────┤
│                   Virtualization                     │ ← Provider manages (all)
├─────────────────────────────────────────────────────┤
│                      Servers                         │ ← Provider manages (all)
├─────────────────────────────────────────────────────┤
│                      Storage                         │ ← Provider manages (all)
├─────────────────────────────────────────────────────┤
│                     Networking                       │ ← Provider manages (all)
└─────────────────────────────────────────────────────┘

When to Use Each

• IaaS: Maximum control, migrating existing apps ("lift and shift")
• PaaS: Focus on code, not infrastructure (startups, new apps)
• SaaS: Just need the service working (email, CRM, collaboration)

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3. Public vs Private vs Hybrid Cloud

Deployment Models

Model	Description	Pros	Cons
Public Cloud	Resources owned by provider, shared across customers	Low cost, no maintenance, elastic	Less control, shared resources
Private Cloud	Dedicated infrastructure for one organization	Full control, security, compliance	High cost, limited scalability
Hybrid Cloud	Combination of public and private	Flexibility, gradual migration	Complexity, integration challenges

When to Use

• Public Cloud: Web apps, dev/test, variable workloads
• Private Cloud: Sensitive data, strict compliance (banks, healthcare)
• Hybrid Cloud: Gradual cloud migration, burst capacity, data sovereignty

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4. Introduction to AWS

Amazon Web Services (AWS) is the world's most comprehensive and widely adopted cloud platform.

AWS History

Year	Milestone
2002	AWS founded (originally for Amazon.com internal use)
2006	S3 and EC2 launched publicly
2010	All of Amazon.com moved to AWS
2024	200+ services, 99 Availability Zones

Why AWS?

• Market leader — Largest cloud provider (~32% market share)
• Most services — 200+ fully-featured services
• Global reach — Data centers in 32 regions worldwide
• Mature ecosystem — Documentation, training, community
• Enterprise-ready — Used by Netflix, Airbnb, NASA, etc.

AWS vs Azure vs GCP

Aspect	AWS	Azure	GCP
Best for	Everything	Microsoft shops	Data/ML
Market share	~32%	~23%	~10%
Services	200+	200+	100+
Strengths	Maturity, breadth	Enterprise, hybrid	ML, Kubernetes

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5. AWS Global Infrastructure

AWS infrastructure is designed for high availability and low latency.

Key Concepts

Concept	Description
Region	Geographic location with multiple data centers (e.g., ap-south-1 = Mumbai)
Availability Zone (AZ)	One or more discrete data centers within a region
Edge Location	CDN endpoints for CloudFront (caching content close to users)
Local Zone	Extends a region closer to end-users for ultra-low latency

Current Scale (2024)

• 32 Regions globally
• 99+ Availability Zones
• 400+ Edge Locations

How to Choose a Region

1. Compliance — Data residency requirements (e.g., data must stay in India)
2. Latency — Closest to your users
3. Service availability — Not all services available in all regions
4. Cost — Pricing varies by region

High Availability Design

                    Region: ap-south-1 (Mumbai)
    ┌──────────────────────────────────────────────────┐
    │                                                  │
    │   ┌─────────────┐       ┌─────────────┐         │
    │   │    AZ-1a    │       │    AZ-1b    │         │
    │   │             │       │             │         │
    │   │   [EC2]     │       │   [EC2]     │         │
    │   │   [RDS]     │  ←──→ │   [RDS]     │ Replica │
    │   └─────────────┘       └─────────────┘         │
    │                                                  │
    └──────────────────────────────────────────────────┘
    
    Best Practice: Deploy across multiple AZs for fault tolerance

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6. Shared Responsibility Model

AWS security is a shared responsibility between AWS and the customer.

The Division

Responsibility	AWS ("Security OF the Cloud")	You ("Security IN the Cloud")
Physical	Data centers, hardware, networking	-
Infrastructure	Compute, storage, database, networking	-
Platform	Managed services (RDS, Lambda)	Configuration, access control
Data	-	Encryption, access policies
Identity	-	IAM users, roles, MFA
Application	-	Code, patching (EC2), firewall rules

Visual Model

┌─────────────────────────────────────────────────────┐
│                 CUSTOMER RESPONSIBILITY              │
│  ┌───────────────────────────────────────────────┐  │
│  │ Customer Data                                  │  │
│  │ Platform, Applications, Identity & Access      │  │
│  │ Operating System, Network & Firewall Config   │  │
│  │ Client-side & Server-side Encryption          │  │
│  └───────────────────────────────────────────────┘  │
├─────────────────────────────────────────────────────┤
│                   AWS RESPONSIBILITY                 │
│  ┌───────────────────────────────────────────────┐  │
│  │ Software: Compute, Storage, Database, Network │  │
│  │ Hardware/AWS Global Infrastructure            │  │
│  │ Regions, Availability Zones, Edge Locations   │  │
│  └───────────────────────────────────────────────┘  │
└─────────────────────────────────────────────────────┘

Key Takeaway

• AWS: Responsible for security OF the cloud (infrastructure)
• You: Responsible for security IN the cloud (your data, configurations)

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7. Well-Architected Framework

AWS Well-Architected Framework helps you build secure, high-performing, resilient, and efficient infrastructure.

The 6 Pillars

Pillar	Focus	Key Questions
Operational Excellence	Run and monitor systems	How do you respond to events?
Security	Protect data and systems	How do you manage identities?
Reliability	Recover from failures	How do you handle changes?
Performance Efficiency	Use resources efficiently	How do you select your resources?
Cost Optimization	Avoid unnecessary costs	How do you decommission resources?
Sustainability	Minimize environmental impact	How do you reduce impact?

Best Practices Summary

1. Operational Excellence

• Perform operations as code (Infrastructure as Code)
• Make frequent, small, reversible changes
• Learn from all operational failures

2. Security

• Implement strong identity foundation (IAM, MFA)
• Enable traceability (CloudTrail, logs)
• Apply security at all layers
• Encrypt data at rest and in transit

3. Reliability

• Automatically recover from failure
• Test recovery procedures
• Scale horizontally (multiple small instances > one large)
• Manage change through automation

4. Performance Efficiency

• Use serverless where possible
• Go global in minutes (multi-region)
• Experiment often

5. Cost Optimization

• Adopt consumption model (pay for what you use)
• Stop guessing capacity (use auto-scaling)
• Analyze and attribute expenditure

6. Sustainability

• Understand your impact
• Maximize utilization
• Use managed services

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TL;DR - Quick Recall

Topic	Key Takeaway
Cloud Computing	On-demand IT resources, pay-as-you-go, no hardware maintenance
IaaS/PaaS/SaaS	IaaS = most control, SaaS = least control, PaaS = balanced
Cloud Types	Public (shared), Private (dedicated), Hybrid (mix)
AWS	Market leader, 200+ services, global infrastructure
Infrastructure	Regions → AZs → Edge Locations (design for multi-AZ)
Shared Responsibility	AWS secures the cloud, you secure what's IN the cloud
Well-Architected	6 pillars: Operations, Security, Reliability, Performance, Cost, Sustainability