The global map is divided into 60+ regions, these are physical locations in which the servers exist. Not all regions are available to everyone, some of them have restrictions on them.
e.g - China and Germany regions are not available to everyone. Some government regions are also hidden.
Each region has one other region which is treated as it’s pair. They are mostly in the same geographic location, for higher speed access. Deployments are done in only one part of the pair, other is untouched. In case of disaster one of them is treated as priority.
e.g - North Europe - West Europe
These are zones which reside inside the regions, these are physically seperate data centers and have their own power, internet etc.
They are basically the tree structure of all the logically related resources. These are logically separated depending upon projects, accounts etc.
Subscriptions is generally the billing unit, all the resources in that subscription are billed to it. One user can have multiple subscriptions.
e.g - Separate subscription for HR, Marketing and Finance
Useful for setting up policies on subscriptions.
Instances of services, created by the user.
There are many different ways to access azure
Like Web Portal, Azure Shell, Visual Studio
These are all handled by Azure Resource Manager API, It can handle public and hybrid cloud models.