Does NW IDM create the Windows account also in MS AD

I am doing the feasible study of implementing NW IDM into our organization. After going through few doucment, I have a question for wich I am unable to get the definite answer.

When a person joins a organization, user account info has to be present into AD to create the user identity into IDM. OR the NW IDM Administrator will be the first point of contact to create the user identity in all SAP applications and Windows account in MS AD. To make it easy, will Windows user account will also be created with NW IDM or not.

It would be helpful, if anyone can suggest the workflow and use of IDM from the point a person joins a organization and how the roles are assigned to him through IDM.