Links are a shortcut for a file or directory which tells any programs that use it where the real location is. Using Links you can access files from multiple locations even across different hard drives.
These are useful for moving physical location of files yet allowing existing software to work with the existing file location.
There are 3 kinds of links in Windows 7, soft links, hard links and Junctions. I found that some software doesn’t handle soft links very well and also Explorer doesn’t distinguish hard links from normal directories, so Junctions worked best for me.
In my case, I installed a Solid State Harddrive (SSD) as the boot partition and some rarely used programs and larger program data were moved to the older Harddrive.
If you have used Linux you may be familiar with the following command to make soft links.
ln -s real_location new_link_location
The equivalent command for Windows 7 to make soft links in Command prompt
mklink /D new_link_location real_location
The command for Windows 7 to make a directory junction in Command prompt
mklink /J new_link_location real_location
Here is an example from one I did recently.
C:\Program Files (x86)>mklink /J "Finale NotePad 2012" "D:\SSDLink\Program Files (HDD)\Finale NotePad 2012"
Junction created for Finale NotePad 2012 <<===>> D:\SSDLink\Program Files (HDD)\Finale NotePad 2012
Update June 2021: I have finally created an application to Manage Directory Junctions to Offload from my SSD.