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Chapter 1

Cloud computing concepts

Last updated November 2026about 4 min read

Key takeaways

  • Cloud computing is the on-demand delivery of computing resources, servers, storage, databases, networking and software, over the internet, paid for as used rather than bought and maintained as physical infrastructure.
  • The service models differ in how much the customer manages: IaaS the most (everything from the operating system up), PaaS less (only their own applications on a managed runtime), SaaS the least (just using a ready-made application).
  • The deployment models are private (dedicated to one organisation), public (shared and run by a third-party provider), hybrid (private and public combined) and community (shared by a group of organisations with common concerns).
  • Five characteristics mark a cloud service: on-demand self-service, broad network access, resource pooling, rapid elasticity and measured, pay-for-use service.
  • Virtualization is the core enabling technology of the cloud, alongside service-oriented architecture, grid computing and utility computing; Azure, AWS and GCP are the three dominant public cloud providers.

Cloud computing is the on-demand delivery of computing resources, servers, storage, databases, networking, software, over the internet, paid for as used rather than bought and maintained as physical infrastructure.

Cloud computing service models, distinguished by how much of the stack the provider manages versus the customer:

Software as a Service (SaaS)
The provider delivers a complete, ready-to-use application, e.g. an email or office suite, the customer manages nothing underneath it.
Platform as a Service (PaaS)
The provider manages the underlying infrastructure and runtime, the customer deploys and manages their own applications on top.
Infrastructure as a Service (IaaS)
The provider delivers raw computing resources, virtual machines, storage, networking, the customer manages everything from the operating system up.

Cloud deployment models:

Private cloud
Infrastructure dedicated to a single organisation, for greater control and security.
Public cloud
Infrastructure shared across many customers, owned and run by a third-party provider.
Hybrid cloud
Combines private and public cloud, workloads can move between them as needed.
Community cloud
Shared infrastructure serving a specific group of organisations with common concerns, e.g. a shared regulatory requirement.

Characteristics of cloud computing:

  • On-demand self-service: resources provisioned without human intervention from the provider.
  • Broad network access.
  • Resource pooling across many customers.
  • Rapid elasticity: scaling up or down quickly.
  • Measured, pay-for-use service.

Cloud computing technologies, the foundations that make elastic, shared cloud infrastructure possible:

Virtualization
Running multiple isolated virtual machines on one physical machine, the core enabling technology of the cloud.
Service-Oriented Architecture (SOA)
Structures software as a collection of independent, interoperable services.
Grid computing
Pools computing resources across multiple locations to work on a shared task.
Utility computing
Delivers computing resources as a metered service, the same pay-as-you-go model electricity or water uses.

Advantages of Microsoft Azure:

  • Broad global infrastructure.
  • Deep integration with other Microsoft enterprise tools.
  • A wide range of managed services (including the SQL and Synapse services covered in the next chapter).
  • Strong compliance certifications.

Disadvantages:

  • Cost can be complex to predict and control at scale.
  • Its breadth of services carries a real learning curve.

Examples of cloud service providers: Microsoft Azure, Amazon Web Services (AWS), and Google Cloud Platform (GCP), the three dominant public cloud providers.

Exam tip

The three service models (SaaS, PaaS, IaaS) are commonly tested by asking how much a customer has to manage themselves, IaaS is the most (everything above the hardware), SaaS is the least (just using the application), PaaS sits in between.

Test Your Knowledge

3 questions on this chapter
Question 1 of 3A Nairobi fintech rents virtual machines, storage and networking from a cloud provider, then installs and patches its own operating system, database software and application on them. Which service model is it using?
Pick an option first
Question 2 of 3Several Kenyan Saccos that answer to the same regulator share one cloud infrastructure set up to meet that common regulatory requirement. Which deployment model is this?
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Question 3 of 3Which cloud computing technology runs multiple isolated virtual machines on one physical machine, and is described as the core enabling technology of the cloud?
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