You can add a hashtag to anything you like and feel is appropriate. Go into your profile page and click on Discover at the bottom left on page and at the top right of next page click Tags and browse. It will probably take you hours to get through them all but it will give you an idea of the range. Hope this helps.
@angipangi It dfores hrlp thanks & just had a quick look & OMG there are millions & not in alpha order! I get the idea & could be useful. Will need to think what types "buzz words" I might apply a # to! 😕