Provides fine grained access to Resources
Allows to create custom roles as per need
Scopes are hierarchical

Actions

Operations that can be performed on the services present in Azure

Role

An collection of actions that can be performed
An role can be assigned to an user or application identity
Answers question: What can be done ?

Security Principle

Security Principle is an object (Identity) that can be assigned a role
They are objects that can act upon other resources on the network

It can be a User, Group of Users, Service Principle (Service in Azure) or Managed Identity (Role for a specific service)
Answers question: Who can do it ?

Scope

In Azure scope is management as a hierarchy
A scope can be a Management Group, Subscription, Resource Group, Resources
Scope is one or more resource to which role is applied
Answers question: Where can it be done ?

Role Assignment

Attach Role Assignment to a Security Principal on a scope
Role Assignments are additive i.e. assigned permission will be sum of all roles assigned