I could have sworn there was an article related to tags but I guess I remembered that wrong. Here is Medium’s Support Page on Tags:
When you first sign up for Medium, you can follow tags related to subject areas you're interested in. You can customize…help.medium.com
When I signed up for Medium I followed a bunch of tags that I thought were interesting and I use tags to do searches for content when I am thinking of publishing something — just to make sure that I am not reinventing the wheel. My favorite tags that I follow are “This Happened To Me”, “Short Story”, “Pets”, and “Humor”.
Another good way to find interesting stories is to click on the tags at the bottom of a story that you like to find similar stories. Once the search results come up, the default is that Top stories show up first. I click on the “Latest” link to sort by most recently published and have found some hidden gems that way.
Thin Man uses tags differently than most here on Medium. His tags are a way for him to interject a humorous parting comment on what he writes. His tags aren’t all that effective a way to find other stories though. If you click on them, you may find that his is the only story that comes up under that tag.
I hope that helps a bit. I am quite rusty at explaining technical things in a non-technical manner as I haven’t done that in a few years.
Best of luck with your searches!