In my “day job” as an Azure specialist I am often asked for Azure references on various topics. Here is a list of some of the most important references that I have been sending out recently:
Sizes for Windows virtual machines in Azure and Sizes for Linux virtual machines in Azure cover the specifications of the VM sizes that you can run in Azure:
Microsoft server software support for Microsoft Azure virtual machines covers what is (and is not) supported running in an IaaS VM:
Cloud Platform roadmap covers what has been recently released and what Microsoft is working on.
Microsoft Azure and Amazon Web Services covers AWS Compete is a good reference to have if the question of comparing AWS and Azure features comes up.
One additional great resource is the Azure Learning Paths. Azure is so broad that it is difficult to know where to start learning about a particular service or feature. The Learning Paths are step-by-step flowcharts that guide you through the documentation and videos on about 35 of the Azure services. (Not every service is so documented, but the ones that are are well done.) Highly recommended.