What are the cloud deployment models?

Now that we understand what the cloud characteristics are, let's talk about cloud deployment models:

• Private cloud: An infrastructure deployed and maintained by a single organization. Let's say we are a large financial organization (such as a bank or insurance organization), we would like to serve various departments in our organization (from HR, IT, sales, and so on), and we might have regulatory requirements to keep customers' data on-premises – a private cloud can be a suitable solution.
• Public cloud: An infrastructure deployed and maintained by a service provider for serving multiple customers and organizations, mostly accessible over the internet. Naturally, this book will focus on the public cloud model, with reference to various services offered by AWS, Azure, and GCP.
• Hybrid cloud: A combination of a private cloud (or on-premises cloud) and at least one public cloud infrastructure. I like to consider the hybrid cloud as an extension of the local data center. We should not consider this extension as something separate, and we should protect it the same way we protect our local data center.
• Multi-cloud: A scenario where our organization is either using multiple managed services (see the definition of SaaS in the next section) or using multiple public cloud infrastructure (see the definitions of IaaS and PaaS in the next section).