At a minimum, I create at least one SYSImages Picture library in my root SharePoint Site Collection. You may find, due to permissions, that you will create one in other sites as well, mileage will vary.
The Purpose for doing this, is a central (within SharePoint so that you avoid using and depending on outside images) place to put icons and images that you will use on your site for icons, content editor web parts, etc.
Call the picture library whatever you like but...
1. Do not show it on the Quick Launch bar (its for you, not for everyone else)
2. Put all system used images in there
3. When referring to the images in that library in your site, BE SURE to use the relative path to the library and not the full URL as you may find in the future (or now), that you will have multiple AAM's (Alternate Access Mappings), a fancy word for saying 'different URL's to point to your site.
E.g.
FULL URL (don't use):
https://portal.itgroove.org/SYSImages/emailicon.jpg RELATIVE URL (do use):
/SYSImages/emailicon.jpg