What is Main purpose of Azure governance?

The main purpose of Azure Governance is to help organizations enforce standards, security, and compliance by using tools like.
Policies,Rbac,management groups, locks and tags.

How do we provide IAM access to users?

We use RBAC - role based access control and give them , there are privilege roles and least privilege roles , if u assign owner role the user gets full access to azure resources he can view , edit , delete . We can also give them roles like contributor and reader .

40