It's literally the very first post ever posted on Openbook. It clearly states that the first line of tags following the content of the post should be 2 to 3 tags describing the post, starting from the broadest topic to the most specific subject. This is like our "Dewey Decimal System" on Openbook. This is how we categorize information, so that Openbook can be a useful tool, an accessible bank of knowledge that's easily navigated so that we can all use it to learn from each other efficiently. We take the extra time to check what tags are already listed on the "Search" page so we can see if there are pre-existing tags which are suitable to use. We do this to avoid lots of useless tags that all mean the same thing, or mean nothing at all. We try to have one tag for each meaning, so try not to create new tags unless there's no way to describe your post with existing tags.
So please, against all odds, please struggle to describe your post succinctly with three increasingly specific tags, no more, on the first line of tags after the post's content. This makes it easy for all of us to see what the content of a post is about, at a glance, so we don't waste each other's time. If you need to tag it with more than the three tags, just put those tags on a separate line after the first line of tags. Or put them in the text of the post.