Introduction
Cloud computing is the delivery of computing services — servers, storage, databases, networking, software, analytics, and intelligence — over the internet (the “cloud”) to offer faster innovation, flexible resources, and economies of scale. Instead of owning physical data centers or servers, organizations rent access to compute resources on a pay-as-you-go basis from cloud providers.
Why it matters
Cloud computing enables businesses to scale quickly, reduce capital expenditure, accelerate development cycles, and focus on building features rather than maintaining infrastructure. It’s foundational to modern IT architectures, SaaS products (like Salesforce), and digital transformation initiatives.
Service Models
Infrastructure as a Service (IaaS)
IaaS provides virtualized computing resources over the internet. Customers get control over operating systems, storage, and deployed applications while the provider manages hardware. Examples: Amazon EC2, Google Compute Engine, Microsoft Azure VMs.
Platform as a Service (PaaS)
PaaS offers a platform allowing customers to develop, run, and manage applications without dealing with infrastructure. It includes runtime, middleware, and development tools. Examples: Heroku, Google App Engine, Azure App Service.
Software as a Service (SaaS)
SaaS delivers software applications over the internet on a subscription basis. Users access apps through a web browser; the provider handles everything under the hood. Examples: Salesforce, Microsoft 365, Google Workspace.
Deployment Models
Public Cloud
Services run on infrastructure owned by third-party providers and delivered over the public internet. Pros: cost-effective, scalable. Cons: less control over underlying infrastructure.
Private Cloud
Dedicated infrastructure operated for a single organization—either on-premises or hosted. Pros: greater control and security. Cons: higher cost and maintenance overhead.
Hybrid Cloud
Combines public and private clouds, allowing workloads to move between them for flexibility and optimization.
Multi-Cloud
Using multiple cloud providers to avoid vendor lock-in, optimize costs, and leverage best-of-breed services.
Key Benefits
Scalability: Scale resources up or down based on demand.
Cost Efficiency: Pay only for what you use (OPEX vs CAPEX).
Reliability: Built-in redundancy and global availability zones.
Speed & Agility: Provision resources and environments quickly.
Global Reach: Deploy services close to users worldwide.
Common Use Cases
Cloud is used for web and mobile app hosting, data backup and disaster recovery, big data analytics, machine learning, continuous integration/continuous deployment (CI/CD), and SaaS delivery.
Security & Governance Considerations
Security in the cloud is a shared responsibility: the provider secures the infrastructure while you secure data, access controls, and configurations. Key controls include identity and access management (IAM), encryption (in transit and at rest), network segmentation, monitoring, and compliance frameworks (e.g., GDPR, HIPAA).
Quick Example
Example: Uploading a file to Amazon S3 using the AWS CLI.
aws s3 cp ./report.pdf s3://my-bucket/reports/report.pdf
Examples of Major Cloud Providers
AWS (Amazon Web Services) — broadest set of services and global footprint.
Microsoft Azure — strong enterprise integrations (Active Directory, Microsoft 365).
Google Cloud Platform (GCP) — strong data, analytics, and ML offerings.
Salesforce — cloud-first SaaS, CRM, and platform services (Sales Cloud, Service Cloud).
Summary
Cloud computing is a paradigm shift in how IT is delivered and consumed. Understanding the core service models (IaaS, PaaS, SaaS), deployment options (public, private, hybrid), and security responsibilities helps teams choose the right approach for scalability, cost efficiency, and faster innovation.
For interview prep: be ready to explain trade-offs between models, real-world examples you’ve worked on, and how you addressed cloud-related security or cost challenges.