A Guide to All Cloud Models (2025)

The world of cloud computing is filled with acronyms. IaaS, PaaS, SaaS, DBaaS, Hybrid, Multicloud—it can feel like learning a new language. But understanding this language is the key to making smart decisions about technology, security, and architecture.

Consider this your definitive translation guide.

In this article, we will provide clear, practical definitions for every major cloud model. We’ll break them down into two main categories:

Deployment Models: Where your cloud infrastructure lives and who can access it.
Service Models: What kind of service or functionality you get from the cloud.

Let’s dive in.

Table of Contents

Part 1: Cloud Deployment Models (Where the Cloud Lives)

This category defines the architecture and ownership of the cloud environment.

1. Public Cloud

The infrastructure is owned and operated by a third-party provider (like AWS, Google, Microsoft) and is shared by many different organizations over the public internet.

Analogy: A vast public library. Anyone with a library card can access its resources, and the library is responsible for maintaining the building and the books.
Pros: Massive scalability, pay-as-you-go pricing, no hardware maintenance.
Cons: Less control, potential for “noisy neighbors,” may not meet strict regulatory compliance.
Best For: Websites, startups, and applications with fluctuating traffic.

2. Private Cloud

The infrastructure is used exclusively by a single organization. It can be located on-premises or hosted by a third party, but the hardware is completely dedicated.

Analogy: A private, in-home library. You have complete control over every book and who can enter, but you are responsible for all the costs and maintenance.
Pros: Maximum control, enhanced security, easier to meet compliance standards.
Cons: Much higher cost, limited scalability, requires in-house IT expertise to manage.
Best For: Financial institutions, healthcare organizations, and government agencies with sensitive data.

3. Hybrid Cloud

This model combines a private cloud with one or more public clouds, using technology that allows data and applications to move between them.

Analogy: Owning a private library for your rare books, but using your public library card to check out popular novels. You get the best of both worlds.
Pros: Flexibility, ability to keep sensitive data secure while leveraging the public cloud for scalable, less-sensitive workloads.
Cons: Can be complex to set up and manage.
Best For: Businesses that want to gradually migrate to the cloud or have diverse workloads with different security needs.

4. Community Cloud

The infrastructure is shared by several organizations from a specific community with common concerns (e.g., security, compliance, jurisdiction).

Analogy: A shared university research library. It’s only accessible to students and faculty from a few specific universities, who all share the costs and resources.
Pros: Lower cost than a private cloud, with better security and compliance than a public cloud for a specific industry.
Cons: Smaller scale, can be difficult to find a provider that meets the exact needs of the community.
Best For: University systems, hospital groups, or joint government ventures.

5. Multicloud

This refers to the use of multiple public clouds from different providers. For example, using AWS for its web servers, Google Cloud for its machine learning services, and Azure for its Office 365 integration.

Analogy: Having library cards to three different city library systems, allowing you to pick the best or most convenient library for any specific book you need.
Important: This is different from Hybrid Cloud, which involves a mix of public and private infrastructure. Multicloud is a mix of different public providers.
Pros: Avoids vendor lock-in, allows you to pick the best service for the job from any provider.
Cons: Can be very complex to manage and secure across different platforms.
Best For: Mature organizations that want to optimize performance and cost by leveraging the unique strengths of each cloud provider.

Part 2: Cloud Service Models (What You Get from the Cloud)

This category defines the service you are consuming and how much of the tech stack you are responsible for managing.

1. IaaS (Infrastructure as a Service)

The most basic model. You rent the fundamental infrastructure—servers, storage, and networking.

You Manage: The operating system, applications, and data.
Provider Manages: The physical hardware and virtualization.
Example: AWS EC2, Google Compute Engine.

2. PaaS (Platform as a Service)

Provides a complete development and deployment environment in the cloud. You manage your app, the provider manages the platform.

You Manage: Your application code and data.
Provider Manages: The OS, servers, runtime, and all underlying infrastructure.
Example: Heroku, Google App Engine.

3. SaaS (Software as a Service)

A fully-formed software application that you access over the internet, typically via a subscription.

You Manage: Your user account and how you use the software.
Provider Manages: Everything else.
Example: Microsoft 365, Slack, Google Workspace.

4. DBaaS (Database as a Service)

This is a specialized form of PaaS. It’s a cloud service where the provider manages the database, handling tasks like installation, patching, backups, and scaling, while you just use it.

You Manage: Your data, schema design, and queries.
Provider Manages: The database engine, OS, hardware, backups, and high availability.
Example: Amazon RDS, MongoDB Atlas, Azure SQL Database.

5. SECaaS (Security as a Service)

A cloud-delivered model for outsourcing cybersecurity services. Instead of managing security tools on-premise, you integrate your infrastructure with a cloud-based security provider.

You Manage: Your security policies and user access rules.
Provider Manages: The security infrastructure, threat intelligence updates, and maintenance of the tools.
Example: Okta (Identity Management), Cloudflare (DDoS Protection & WAF), Zscaler (Secure Web Gateway).