Cloud Computing¶
What is Cloud Computing?¶
On-demand access to shared computing resources — servers, storage, networking, software — over the internet from a third-party provider. You pay for what you use instead of owning and maintaining physical hardware.
Service Models¶
IaaS — Infrastructure as a Service¶
Rent the basic building blocks: servers, storage, and networking. You manage the OS and everything above it.
Examples: AWS EC2, Microsoft Azure VMs, Google Compute Engine
Best for: Maximum control; teams that want to configure their own stack.
PaaS — Platform as a Service¶
A managed runtime/platform to build and deploy applications. The provider handles the OS, runtime, and infrastructure.
Examples: Heroku, Google App Engine, AWS Elastic Beanstalk
Best for: Developers who want to focus on code, not infrastructure.
SaaS — Software as a Service¶
Pre-built applications delivered over the internet. No installation or maintenance required.
Examples: Gmail, Salesforce, Microsoft Office 365, Slack
Best for: End users consuming software, not building it.
| Model | You manage | Provider manages |
|---|---|---|
| IaaS | OS, runtime, apps | Hardware, networking, storage |
| PaaS | App code, data | OS, runtime, middleware |
| SaaS | Data, user access | Everything else |
Benefits of Cloud Computing¶
| Benefit | Description |
|---|---|
| Pay-as-you-go | No large upfront capital expense — pay only for what you consume |
| Scalability | Scale resources up or down on demand |
| Accessibility | Access resources from anywhere with internet |
| No maintenance burden | Provider handles hardware, patching, and physical security |
| Multi-tenancy | Cost shared across many customers, lowering individual expense |
| High availability | Built-in redundancy — if one server fails, others take over |
Deployment Models¶
Private Cloud¶
Infrastructure provisioned exclusively for a single organization. Can be hosted on-premises or by a third party. Provides maximum control and security.
Best for: Regulated industries (finance, healthcare), sensitive data.
Public Cloud¶
Infrastructure shared across multiple customers and operated by a third-party provider. Open market access with low entry cost.
Examples: AWS, Google Cloud Platform (GCP), Microsoft Azure
Best for: General workloads, startups, teams needing fast provisioning.
Hybrid Cloud¶
A mix of private and public cloud. Sensitive data stays on the private cloud; public-facing services or burst workloads run on the public cloud.
Use case: A hospital keeps patient records on a private cloud but hosts its patient portal on a public cloud.
Community Cloud¶
Shared infrastructure for organizations with common needs (e.g., regulatory compliance, shared mission). Costs and governance are shared among the group.
Example: A group of hospitals sharing HIPAA-compliant infrastructure.
Multicloud¶
Using multiple public cloud providers simultaneously to avoid vendor lock-in or leverage pricing differences.
Example: Compute on AWS, data analytics on GCP, collaboration tools on Azure.
Polycloud¶
Selectively picking the best individual services from different providers rather than committing to one vendor's full stack.
Virtualization¶
Virtualization splits one physical machine into multiple isolated virtual machines (VMs), each with its own OS and resource allocation.
Hypervisors¶
A hypervisor is the software layer that creates and manages VMs.
| Type | Description | Examples |
|---|---|---|
| Type 1 (Bare-metal) | Runs directly on hardware — enterprise | VMware ESXi, Microsoft Hyper-V |
| Type 2 (Hosted) | Runs on top of an existing OS — lighter | VirtualBox, VMware Workstation |
Benefits of Virtualization¶
- Better resource utilization — multiple VMs share one physical machine
- Isolation — each VM is sandboxed; a crash in one doesn't affect others
- Easier disaster recovery — VMs can be snapshotted and restored quickly
- Flexibility — spin up or tear down environments in minutes
Key Terms¶
| Term | Definition |
|---|---|
| VM | Virtual machine — a software-based computer |
| Guest OS | The OS running inside a VM |
| Host OS | The OS running on the physical machine |
| Hypervisor | Software that creates and manages VMs |
| Provisioning | Allocating and configuring resources for use |
| Elasticity | Automatically scaling resources in response to demand |
| Scalability | Ability to increase capacity to handle more load |
| Multitenancy | Multiple customers sharing the same physical resources |
Industry Snapshot (2024)¶
- SaaS accounts for approximately 54% of global cloud revenue
- Private cloud accounts for 46%+ of market revenue
- Hybrid cloud is growing at 20%+ annually
- In the EU, 45.2% of enterprises purchased cloud services in 2023
- Agentic AI platforms — cloud-hosted AI agents — are beginning to reshape developer and enterprise workflows