By default, Windows will use the index when searching to give you faster search results. The search index only includes your selected locations. These locations can be filtered for what file types (extensions), file properties, and file contents you want indexed.
Libraries gather folders that are stored in different locations so you can browse them in one place. You can include folders and drives to a library as you like.
By default, users in Windows are able to add locations on removable drives to libraries and as indexed locations.
This tutorial will show you how to enable or disable the ability to add locations on removable drives to libraries and as indexed location for all users in Windows 8.1 and Windows 10.