Example scenario - I have a vulnerability that applies to Apache, and I want to find all hosts running Apache web servers, regardless of OS.
Using Asset Search
Select your target hosts (asset groups, IP's or All)
Select QID 86000, 86001 - with results containing apache (enter apache into the text box)
The resulting list will show all hosts identified with Web Server Version (QID 86000) and SSL Web Server Version (QID 86001) with a banner containing "Apache".
You could find similar results if you search for IIS or other banners.