Active Directory allows you to create contacts to hold information about 3rd parties like their phone numbers and e-mail addresses. This kind of information can also be added to a user account, however creating a contact to hold this information means that contacts cannot be used to login like a user can and thus is less of a security concern.
Security Identifier (SID)
The fundamental difference between a user account and contact is a contact does not have a security identifier or SID. A SID is used with security in Windows. Any time that you assign permissions to objects or files the SID is required. Since a contact does not have a SID, by design it cannot be used with security. Also since a contact does not have a SID it cannot be used to login.
Benefits of Active Directory Contacts
Having contacts for your organization stored in Active Directory means that any users can perform searches for this information. Since the contact data is stored in the Active Directory database, this means that data is stored once and thus is also easy to update. Without a centralized system like this, individual users would store multiple copies of the same data making it hard to update when changes occur.
Windows 7 Contacts
Windows supports contacts that can be stored on the local Windows computer. This was first introduced in Windows Vista. The contact data is stored in an XML file which means that it can also be used by non Microsoft software. Windows 7 does not come with any software that uses contacts. Contacts in Windows 7 are there for back compatibility only. The main use of contacts in Windows Vista would most likely be Windows Mail which is no longer included in Windows 7. Microsoft offer a free e-mail software called Windows Live Mail that can be download from the Microsoft web site. This software does not support contacts, but any existing contacts can be imported.
Creating a contact in Active Directory
To create a contact, open Active Directory Users and Computers.
Right click where you want to create the contact and select new contact.
Complete the wizard in order to create the contact.
To configure additional options and properties for the contact, right click the contact and open the properties.
Even though contacts cannot be used with security, a contact can also be a member of group. Software like Exchange can utilize these contacts.
“Windows 7 Inside Out” Microsoft Press, pg 276
“Windows Contacts” http://en.wikipedia.org/wiki/Windows_Contacts
“Is Windows Contacts integrated with Windows Live Mail in Windows 7?” http://answers.microsoft.com/en-us/windows/forum/windows_7-networking/is-windows-contacts-integrated-with-windows-live/640d77c1-5dd3-4a59-888c-07556ee695a5
“Looking for Windows Mail?” http://windows.microsoft.com/en-us/windows7/looking-for-windows-mail