An active directory is a service that is provided by Microsoft that stores information about items on a network so the information can be easily made available to specific users through a logon process and network administrators. By using an Active Directory it is possible to view an entire series of network objects from a single point and obtain an overall hierarchal view of the network.
If you are a computer administrator for a large corporation or organization, you can easily update all end users computers with new software, patches and files simply by updating one object in a forest or tree.
Because each object fits into a set schema and has specific attributes, a network administrator can easily clear a person on a set tree or instantly give or deny access to select users for certain applications. The Microsoft servers use trust to determine whether or not access should be allowed. Two types of trusts that Microsoft active directories incorporate are transitive trusts and one way non transitive trusts. A transitive trust is when there is a trust that goes further than two domains in a set tree, meaning two entities are able to access each other's domains and trees.
A one way transitive trust is when a user is allowed access to another tree or domain; however, the other domain does not allow access to the further domains. This can be summed up as a network administrator and end user. The network administrator can access most trees in the forest including a specific end user's domain. However, the end user, while able to access his or her own domain, cannot access other trees.
It is important to note that active directories are a great way to organize a large organization or corporation's computers' data and network. Without an active directory, most end users would have computers that would need to be updated individually and would not have access to a larger network where data can be processed and reports can be created. While active directories can be technical to a good extent and require considerable expertise to navigate, they are essential to storing information and data on networks.