Labels
I've just discovered what this site calls labels, which act like keywords. Clicking on one of them will call up a page with all the posts that have that label. E.g., clicking on an audio label will call up all the posts with the audio label, which would be handy if one is looking for audio content.
I have gone back and added labels to all the posts on this blog so far, and I will add appropriate labels to future posts as well.
Update: “Labels” have been renamed “tags” on this blog. See this post for more details.