A link allows you to organize and manage all project-related data in one location. A link is a direct representation of an object that can reside anywhere in Project Explorer. While a link can reside anywhere in the Project Explorer, the target of the link resides in one place only. Links can be created for files, folders, items, and change orders.
Since a link is a direct representation of a target object, it has all of the properties of the target and will appear to be almost identical to the target. Since the link has the same name as the target, the defining difference between a link and a target is the shortcut overlay 
on the link's icon. For example, in the following image, the link is the child object listed.
All links l have the same icon as the target with the addition of the shortcut overlay.
How Commands Affect Links
With only two exceptions, all commands executed on a link are executed on the target object. The change made to the target object is then represented by the link. For example, when a user executes a rename command on a link to a file, the target file is renamed. The changed name is shown on the target and the link.
The two exceptions to this rule are the Delete Command and the Move command. These commands affect the link only and not the target file.