.NET Active Directory Wrapper    
Access Active Directory From Your C# or VB .Net Code
 

Active Directory
Introduction
Objects
Object Properties

DirectoryServices Namespace
Introduction
DirectoryEntry Class

How to .. in C# .NET
Create User
Disable User
Enable User
Authenticate a User
Change User Password
Get DirectoryEntry of a user
Get Users in a Group
Get Object Property

Other Resources
References

Active Directory Objects

Information in Active Directory are stored as objects.

An object can be uniquely identified by its distinguished name.

For example,

CN=Joe,OU=Cabinet,DC=WhiteHouse is the distinguished name for user Joe who is in the Cabinet of White House

CN is the Common Name, or the name used to identify the object. In this case it's Joe

OU is the Orginazational Unit which the object Joe belongs to. In this case its Cabinet.

DC is the Domain Controller of the object. It is often the name of the organization.