Overview
Cloud computing is the delivery of computing services—servers, storage, databases, networking, software, analytics, and intelligence—over the internet (“the cloud”). Instead of owning and maintaining physical data centers and servers, organizations can rent access to computing resources from cloud providers on-demand. This model enables faster innovation, flexible resources, and economies of scale.
Definition
At its core, cloud computing provides on-demand access to shared resources via the internet. Resources are managed by the cloud provider and can be scaled up or down automatically or manually based on demand.
Primary Service Models
Cloud services are typically categorized into three main models:
IaaS (Infrastructure as a Service): Provides virtualized computing resources over the internet—virtual machines, storage, and networks. Example providers: AWS EC2, Azure Virtual Machines, Google Compute Engine.
PaaS (Platform as a Service): Offers platforms to develop, run, and manage applications without dealing with underlying infrastructure. Example providers: Heroku, Google App Engine, AWS Elastic Beanstalk.
SaaS (Software as a Service): Delivers software applications over the internet on a subscription basis. Users access apps through web browsers. Example providers: Salesforce, Microsoft 365, Google Workspace.
Deployment Models
Public Cloud: Services provided over the public internet and shared across organizations. High scalability and cost-efficiency.
Private Cloud: Cloud environment dedicated to a single organization, offering greater control and security.
Hybrid Cloud: Combination of public and private clouds, enabling data and application portability between them.
Key Benefits
Scalability: Scale resources up or down quickly to match demand.
Cost Efficiency: Pay-as-you-go pricing reduces upfront capital expenditure.
Agility & Speed: Faster provisioning and development cycles.
Reliability: Built-in redundancy and managed services improve availability.
Common Use Cases
Application hosting and web services
Big data analytics and machine learning
Disaster recovery and backups
DevOps, CI/CD pipelines, and test environments
Security and Compliance Considerations
Cloud providers offer robust security features, but shared responsibility applies: providers secure the infrastructure while customers must secure data, access, and configurations. Important topics include identity and access management (IAM), encryption (at-rest and in-transit), network segmentation, monitoring, and compliance certifications (e.g., ISO, SOC, GDPR).
Quick Example — Launching a VM (AWS CLI)
The following is a minimal AWS CLI example to start an EC2 instance:
aws ec2 run-instances --image-id ami-0abcdef1234567890 --count 1 --instance-type t3.micro --key-name MyKeyPair --security-group-ids sg-01234567
Interview Tip
When answering interview questions about cloud computing, mention the service models (IaaS/PaaS/SaaS), deployment models (public/private/hybrid), and real-world examples (AWS, Azure, GCP). Also, highlight trade-offs like cost vs. control and the shared responsibility model.