Plugins - search results

If I go to Settings -> Plugins and type something in the search, what is the algorithm that decides which plugins are going to appear? Of course, I assume that this is based on description, title, tags of a plugin... But for example, does the plugin have to have some popularity before it appears there? Or does it show all plugins (including the ones have been published but never installed by anyone or only by a small number of users). Is there anything else that determines if a plugin appears there or not?