When IT resources such as computing servers, storage, development platforms, applications, and so on are made available as a service over the internet and can be provisioned on demand using a publicly available self-service portal, such an offering is called a public cloud. Public clouds offer rapid elasticity and limitless scalability. They provide a measured service in which users are billed based on their usage.

Public clouds are hosted and managed using datacenters that belong to cloud service providers. The resources can be shared by multiple customers. This feature is called multi-tenancy. Sharing resources helps in reducing costs. However, there is reduced control over the resources in a public cloud than in a private cloud, because the underlying infrastructure is owned by the service provider. The level of control depends on the specific cloud delivery model.

There are many public cloud providers on the market, such as Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform (GCP). We will be covering the AWS cloud in detail in this book.

Advantages of a public cloud:

• No administration and maintenance costs
• Simple and easy to use
• Quickly available on demand

Disadvantages of a public cloud:

• Security is a concern as data goes to a public network
• Lack of full control over the cloud