Computer Cloud Computing
Cloud computing means using computing resources — servers, storage, databases, software, networking — over the internet instead of running them on your local computer. Instead of buying and maintaining expensive hardware yourself, you rent computing power and storage from large data centres operated by cloud providers, paying only for what you use.
The word "cloud" refers to the internet itself — early network diagrams drew the internet as a cloud shape to represent the complex infrastructure that users do not need to see or manage.
The Shift: Local vs Cloud
BEFORE CLOUD: WITH CLOUD:
Your Computer Your Computer
┌──────────────┐ ┌──────────────┐
│ Your files │ │ Browser/App │
│ Your apps │ └──────┬───────┘
│ Your backup │ │ internet
│ │ ┌──────▼───────┐
└──────────────┘ │ Cloud Server │
│ Your files │
Everything local. │ Your apps │
If the drive fails, │ Your backup │
everything is gone. └──────────────┘
Accessible from any device.
Provider handles backups.
Three Types of Cloud Services
1. IaaS – Infrastructure as a Service
IaaS provides virtualised computing infrastructure over the internet. You rent virtual machines, storage, and networking. You install and manage your own operating system and applications, but the physical hardware is the cloud provider's responsibility.
Think of IaaS as renting an empty plot of land. You build whatever you want on it — the land owner just provides the space and utilities.
Examples: Amazon Web Services (AWS) EC2, Microsoft Azure Virtual Machines, Google Compute Engine.
Best for: Developers, large companies, DevOps teams who need flexible infrastructure.
2. PaaS – Platform as a Service
PaaS provides a ready-made platform for developers to build, test, and deploy applications. The cloud provider manages the servers, operating system, runtime environment, and middleware. You only manage your application and data.
Think of PaaS as renting a furnished workshop. The tools, workbench, and power tools are there — you just bring your project.
Examples: Google App Engine, Microsoft Azure App Service, Heroku.
Best for: Developers who want to build apps without managing the underlying infrastructure.
3. SaaS – Software as a Service
SaaS delivers complete, ready-to-use applications over the internet. You access the software through a web browser or app — no installation required. The cloud provider manages everything: servers, OS, middleware, data, and the application itself.
Think of SaaS as eating at a restaurant. You just order and eat — the kitchen, the cooking, the cleaning is entirely handled for you.
Examples: Gmail, Google Docs, Microsoft 365, Zoom, Dropbox, Salesforce, Netflix.
Best for: Everyone — businesses and individuals who want ready-to-use software.
IaaS vs PaaS vs SaaS Comparison
│ IaaS │ PaaS │ SaaS
────────────────────┼────────┼────────┼────────
Application │ You │ You │Provider
Data │ You │ You │Provider
Runtime/Middleware │ You │Provider│Provider
OS │ You │Provider│Provider
Servers/Networking │Provider│Provider│Provider
Control │ Most │ Medium │ Least
Responsibility │ Most │ Medium │ Least
Cloud Deployment Models
Public Cloud
Resources are owned and operated by a third-party cloud provider (AWS, Azure, Google Cloud) and delivered over the internet. Multiple customers share the same physical infrastructure, though their data is isolated from each other. Cost-effective and scalable — ideal for most businesses.
Private Cloud
Resources are used exclusively by one organisation. The infrastructure can be on-premises (in the company's own data centre) or hosted by a third party. Offers greater control and security but costs more than public cloud.
Hybrid Cloud
A combination of public and private cloud. Sensitive data stays on the private cloud; less sensitive workloads run on the public cloud. This gives organisations flexibility to scale in the public cloud while keeping critical data secure in the private cloud.
Hybrid Cloud Architecture: ┌──────────────────┐ ┌────────────────────┐ │ Private Cloud │◄────►│ Public Cloud │ │ (sensitive data, │ │ (scalable workloads│ │ core systems) │ │ website traffic) │ └──────────────────┘ └────────────────────┘
Key Benefits of Cloud Computing
Scalability
You can instantly scale resources up or down based on demand. An e-commerce site can scale up on a festive sale day to handle 10× normal traffic, then scale back down the next day — paying only for the extra capacity it used.
Cost Efficiency
You pay for only what you use (pay-as-you-go). No need to buy expensive servers that sit idle most of the time. Capital expenditure (buying hardware) turns into operational expenditure (monthly service costs).
Accessibility
Access your files and applications from any device, anywhere in the world, as long as you have an internet connection. A document saved to Google Drive on your office computer is instantly available on your phone at home.
Reliability and Disaster Recovery
Major cloud providers operate multiple data centres in different geographic locations. If one data centre experiences a fire or power failure, your data and services automatically fail over to another location. This level of redundancy would be prohibitively expensive to build privately.
Automatic Updates
The cloud provider handles server maintenance, OS updates, and security patching. You always use the latest, most secure version of infrastructure without manual updates.
Cloud Security Considerations
Storing data with a cloud provider requires trusting that provider with your information. Key security responsibilities include:
- Choosing providers with strong security certifications (ISO 27001, SOC 2).
- Enabling encryption for data at rest and in transit.
- Using strong authentication and MFA for cloud accounts.
- Understanding the shared responsibility model — the provider secures the infrastructure; you secure what runs on it.
Major Cloud Providers
Provider │ Parent Company │ Key Services ─────────────────────┼────────────────┼──────────────────────────────── AWS (Amazon Web Svcs)│ Amazon │ EC2, S3, Lambda, RDS Microsoft Azure │ Microsoft │ VMs, Azure SQL, Azure AI Google Cloud (GCP) │ Google │ Compute Engine, BigQuery, Vertex AI IBM Cloud │ IBM │ Enterprise AI, Watson Oracle Cloud │ Oracle │ Database, ERP cloud
Everyday Cloud Services You Already Use
Cloud computing is not just for businesses. Most individuals already use cloud services daily:
- Gmail or Outlook — email stored and processed in the cloud
- Google Drive or OneDrive — files stored in the cloud
- YouTube or Netflix — video streamed from cloud servers
- WhatsApp or iMessage — messages routed through cloud infrastructure
- Spotify or Apple Music — music streamed from cloud servers
- Instagram or Facebook — photos and data stored in cloud data centres
The cloud is not a distant technical concept — it already powers the digital tools most people use every hour of every day.