Clusters allow us to group some tags on a book together - as part of the same event, plot line, character, or culture. They are groups of tags that are related to each other on that specific book, describing different aspects of one thing. Instead of tagging the protagonists as "Teenage Mutant Ninja Turtles", a cluster could connect the tags "Teenager", "Mutant", "Ninja" and "Turtle" (though of course, in this case the combination of all four is worth a single combined tag).
Clusters can (but don't have to) be named, so it's easier to keep track of what, exactly, the tags have in common. Cluster names can be character names, places, cultures, events or descriptive words like "Protagonist backstory" or "Enemy alien culture." There can be multiple clusters per book, and the same tag can show up on several clusters.
Like modifiers, using clusters is optional. While all tags have a type and a relevance level, they don't need to have modifiers or be grouped in a cluster. These features help add nuance for in-depth tagging, but they are not necessary to use.
Keep reading to learn about tag pages, where we show detailed descriptions of our tags.