Pin or Thumbtack by a Store's Name

[whimsywhim]

This is a very basic question that I am embarrassed to ask.  I can't find the answer anywhere, and when I hover over it, nothing shows up.

What is that pin or thumbtack next to a store's name indicate?  When I click on it, it turns white.  

Thank you.

[PenguinPower]

That pins your stores so that they show when you look at the “my stores” tab and “pinned”, rather than “all” is selected (which is also the default). If you accidentally unpin one, it can be startling, as it can look like your store has vanished. 

[whimsywhim]

Thank you!!