Directory service

Directory services are software systems that store, organize and provide access to directory information in order to unify network resources.

Active directory

Active Directory is a database that keeps track of all the user accounts and passwords in your organization. It allows you to store your user accounts and passwords in one protected location, improving your organization’s security.

Courtesy: is Active Directory
Think of Active Directory as the “contacts” app on your mobile device. The “contacts” app itself would be your Active Directory. Your individual contacts would be the “objects”, and the address, email and phone information for each contact would be the “values” in your Active Directory. The “objects” aren’t just limited to people and users. It can also contain “group objects”such as computers, printers and so forth.

Azure active directory

Azure Active Directory is an identity and management solution, so it provides the ability to assign identities, user objects and manage those identities as part of this directory listing using native Azure tools, they’re management tools. It’s an authentication solution, so it provides the ability to authenticate access to resources such as applications, for example. You can deploy applications and then manage who is allowed to authenticate to those applications. Who is allowed to access the authentication using the Active Directory authentication mechanisms?

If you have Office365 or Microsoft 365, you already have Active Directory

Azure AD Resources