Cloud computing is often broken down into three different types of services, as follows:

• Infrastructure as a Service (IaaS): This is the fundamental block on top of which everything cloud-based is built. IaaS is usually a computing resource in a virtualized environment. It offers a combination of processing power, memory, storage, and network. The most common IaaS entities you will find are virtual machines (VMs), network equipment, such as load balancers or virtual Ethernet interfaces, and storage such as block devices. This layer is very close to the hardware and gives you the full flexibility that you would get deploying your software outside of a cloud. If you have any physical knowledge about data centers, it will also mostly apply to this layer.
• Platform as a Service (PaaS): This layer is where things start to get really interesting with the cloud. When building an application, you will likely need a certain number of common components, such as a data store and a queue. The PaaS layer provides a number of ready-to-use applications to help you build your own services without worrying about administrating and operating those third-party services such as database servers.
• Software as a Service (SaaS): This layer is the icing on the cake. Similar to the PaaS layer, you get access to managed services, but this time these services are a complete solution dedicated to certain purposes, such as management or monitoring tools.

This book covers a fair amount of services of the PaaS and SaaS types. When building an application, relying on these services makes a big difference when compared to the more traditional environment outside of the cloud.

Another key element to success when deploying or migrating to a new infrastructure is to adopt a DevOps mindset.