What is AWS and why is it used? | AWS Interview Question

Amazon Web Services (AWS) is the world’s leading cloud computing platform provided by Amazon. It offers hundreds of cloud-based services that help businesses, startups, developers, governments, and enterprises build, deploy, manage, and scale applications without owning physical infrastructure.

AWS provides on-demand computing resources such as:

Virtual servers
Storage systems
Databases
Networking
Artificial Intelligence services
Security services
Analytics platforms
DevOps tools
Serverless computing
Machine learning infrastructure

Simple Definition: AWS is a cloud computing platform that allows users to rent computing resources over the internet instead of purchasing and maintaining physical servers.

Introduction to Cloud Computing

Before understanding AWS deeply, it is important to understand cloud computing.

Traditionally, companies purchased physical servers, networking equipment, storage devices, cooling systems, and data center infrastructure to run applications.

This approach had many challenges:

Very high infrastructure cost
Complex maintenance
Hardware failures
Scalability problems
Slow provisioning
Disaster recovery complexity

Cloud computing solved these problems by allowing organizations to access computing resources over the internet.

Traditional Infrastructure vs Cloud Computing

Traditional Data Center	Cloud Computing
Buy physical servers	Rent resources on demand
High upfront cost	Pay-as-you-go pricing
Manual scaling	Automatic scaling
Weeks for provisioning	Minutes or seconds
Hardware maintenance required	Managed by cloud provider

History of AWS

Amazon launched AWS officially in 2006. Initially, AWS started with services like:

Amazon S3 (Storage)
Amazon EC2 (Virtual Servers)

Over time, AWS expanded rapidly and became the largest cloud provider in the world.

Today, AWS operates globally with millions of customers, including:

Netflix
Airbnb
NASA
Adobe
Samsung
BMW
Unilever

Why AWS Became So Popular

AWS became successful because it solved major infrastructure problems for businesses and developers.

Main Reasons

On-demand infrastructure
Global availability
Scalability
Reliability
Security
Automation
Cost optimization
Innovation speed

Core AWS Concepts

1. Regions

AWS operates multiple data center locations worldwide called Regions.

Examples:

US East (N. Virginia)
Asia Pacific (Mumbai)
Europe (London)

Why Regions Matter

Low latency
High availability
Compliance requirements
Disaster recovery

2. Availability Zones (AZs)

Each AWS Region contains multiple Availability Zones.

An Availability Zone is an isolated data center with independent power, cooling, and networking.

Example

Mumbai Region
   |
   |-- AZ-1
   |-- AZ-2
   |-- AZ-3

If one Availability Zone fails, applications continue running from another zone.

3. Edge Locations

AWS Edge Locations are used by CloudFront CDN to deliver content closer to users globally.

How AWS Works

AWS provides infrastructure as internet-accessible services.

Example Workflow

Developer Creates EC2 Server
        |
AWS Allocates Virtual Machine
        |
Application Deployed
        |
Users Access Application

Main AWS Service Categories

Category	Examples
Compute	EC2, Lambda, ECS
Storage	S3, EBS, EFS
Database	RDS, DynamoDB
Networking	VPC, Route53, CloudFront
Security	IAM, KMS, WAF
DevOps	CodePipeline, CodeBuild
Monitoring	CloudWatch, X-Ray

AWS Compute Services

Amazon EC2

EC2 (Elastic Compute Cloud) provides virtual servers in the cloud.

Features

Scalable virtual machines
Custom CPU and memory
Auto scaling
Flexible pricing

Example Use Cases

Web applications
Microservices
Backend APIs
Gaming servers

AWS Lambda

Lambda is a serverless computing service.

Developers run code without managing servers.

Workflow

User Uploads File to S3
        |
Lambda Triggered
        |
Code Executes Automatically

Benefits

No server management
Automatic scaling
Pay only for execution time

AWS Storage Services

Amazon S3

Amazon S3 (Simple Storage Service) is object storage used for storing files, backups, videos, images, logs, and static websites.

Features

Highly durable
Virtually unlimited storage
Versioning support
Lifecycle management

Use Cases

Website hosting
Data lakes
Backup storage
Media storage

Amazon EBS

Elastic Block Store provides persistent storage for EC2 instances.

Amazon EFS

Elastic File System provides shared file storage for multiple servers.

AWS Database Services

Amazon RDS

Relational Database Service (RDS) is a managed database service.

Supported Databases

MySQL
PostgreSQL
Oracle
SQL Server

Advantages

Automated backups
Replication
Automatic patching
High availability

DynamoDB

DynamoDB is a fully managed NoSQL database service.

Characteristics

High performance
Automatic scaling
Serverless architecture

AWS Networking Services

Amazon VPC

Virtual Private Cloud allows organizations to create isolated private networks inside AWS.

Features

Subnets
Routing tables
Security groups
Network ACLs

Route 53

Route 53 is AWS DNS and traffic routing service.

CloudFront

CloudFront is AWS Content Delivery Network (CDN).

It delivers content globally with low latency.

AWS Security Services

IAM (Identity and Access Management)

IAM controls user access and permissions.

Key Concepts

Users
Roles
Policies
Permissions

Example

Developer Role
   |
Access to EC2
No Access to Billing

AWS KMS

Key Management Service handles encryption keys.

AWS WAF

Web Application Firewall protects applications from attacks.

AWS DevOps Services

CodePipeline

Automates CI/CD workflows.

CodeBuild

Compiles and tests applications automatically.

CodeDeploy

Automates deployments.

AWS Monitoring Services

CloudWatch

CloudWatch monitors infrastructure, applications, logs, and metrics.

Metrics Monitored

CPU usage
Memory usage
Disk activity
Application logs

X-Ray

AWS X-Ray helps trace microservice requests.

Cloud Service Models

1. IaaS (Infrastructure as a Service)

Provides infrastructure resources.

Examples

2. PaaS (Platform as a Service)

Provides application deployment platforms.

Examples

Elastic Beanstalk
RDS

3. SaaS (Software as a Service)

Complete software solutions delivered over internet.

Why AWS is Used

1. Scalability

AWS can scale applications automatically.

Low Traffic -> 2 Servers
High Traffic -> 100 Servers

2. Cost Optimization

Organizations pay only for resources used.

3. High Availability

Multi-region and multi-AZ architecture improves reliability.

4. Global Reach

AWS operates globally, enabling worldwide deployments.

5. Security

AWS provides enterprise-grade security features.

6. Automation

Infrastructure can be automated using:

CloudFormation
Terraform
CI/CD pipelines

7. Innovation Speed

Developers launch applications rapidly without waiting for hardware procurement.

Real-World AWS Use Cases

1. Netflix

Netflix uses AWS for:

Video streaming
Global scalability
Content delivery

2. E-Commerce Platforms

Frontend -> CloudFront
Backend APIs -> EC2/EKS
Database -> RDS
Cache -> Redis

3. Banking Applications

AWS supports secure, compliant, highly available banking systems.

4. AI and Machine Learning

AWS provides:

SageMaker
Bedrock
Rekognition
Comprehend

Advantages of AWS

Scalability
Reliability
Global infrastructure
Security
Automation
Managed services
Innovation speed

Disadvantages of AWS

Complex pricing
Steep learning curve
Vendor lock-in risks
Cost management challenges

AWS vs Traditional Data Centers

Traditional Data Center	AWS Cloud
Physical hardware purchase	Virtual infrastructure
Manual scaling	Automatic scaling
Limited global presence	Worldwide infrastructure
High maintenance	Managed services

AWS Shared Responsibility Model

AWS follows a shared responsibility model.

AWS Responsibility	Customer Responsibility
Physical security	Application security
Networking infrastructure	IAM permissions
Hardware maintenance	Data encryption

Production Architecture Example

Users
   |
CloudFront CDN
   |
AWS WAF
   |
Application Load Balancer
   |
EKS Kubernetes Cluster
   |
Docker Containers
   |
RDS Database
   |
Redis Cache
   |
CloudWatch Monitoring

Future of AWS

AWS continues expanding in:

Artificial Intelligence
Generative AI
Serverless computing
Quantum computing
Edge computing
IoT platforms

Interview Answer

AWS (Amazon Web Services) is a cloud computing platform that provides on-demand infrastructure and managed services such as virtual servers, storage, databases, networking, security, analytics, and AI services over the internet.

AWS is used because it allows organizations to build scalable, secure, highly available, and cost-efficient applications without managing physical infrastructure.

It supports cloud-native architectures, DevOps automation, serverless computing, microservices, AI/ML workloads, and enterprise-grade production deployments.

Quick Summary Table

Concept	Explanation
AWS	Amazon cloud computing platform
EC2	Virtual servers
S3	Object storage
RDS	Managed database service
Lambda	Serverless computing
Main Benefit	Scalable cloud infrastructure

Useful Internal Links

Final Conclusion

AWS transformed the technology industry by making enterprise-grade infrastructure available on demand over the internet.

Today, AWS powers millions of applications globally, from startups to Fortune 500 enterprises.

By combining scalability, automation, security, reliability, global infrastructure, and innovation, AWS became the foundation of modern cloud-native computing.