An Azure resource group is something provided by Azure Resource Manager (ARM). It gives you the option to group Azure resources; for example, a useful option of resource groups is collecting all resources that belong to one Azure service/solution into a resource group. An example for this may be a virtual machine in Azure consisting of different resources, such as IP address, NIC, storage, CPU, and so on. Collecting all those resources in one resource group provide a great overview even in complex environments.
Resource groups do not support nesting. This means that you cannot place one resource group into another to define hierarchies. It is a one-level organizational option that provides an easy way to set up policies and roles, and even makes removing Azure resources that belong to an Azure solution quite easy, because you just have to delete the complete resource groups and all resources from within are deleted automatically. If you were to do this manually, you would...