When you list your self-published books on Amazon, B&N or pretty much any other store, you're going to have the option of adding tags. You should always do this, because tagging matters.
Words, Words, Words
Seems like there's always one more thing to do, right? It's not enough to write a book. You have to edit it and format it. Don't forget the cover! Now you need a blurb. Have you published it yet? What's the price? Check the layout! Oh, and now add a bunch of words.
Tagging can feel like a stumbling block on the road to making your work publicly available. It's one of the very last things you have to do in a process that can take many years to complete, and it's easy to rush through. You can simply ignore it. You can plug in a handful of words without half thinking about it. And you can move on.
But if you do it this way, you're automatically decreasing your chances of selling that book. Tagging matters. Why else would all the bookstores be using it?
Tagging Your Books
So, you've used a search engine before. I've got one on this blog. If you want to find a Writing 101 post about using commas, for example, you can just type comma into the search box and see all the related posts. This is pretty much how all search engines work, especially when it comes to online bookstores. The tags you add to your books are the words that book buyers will use to search for (and find) your books.
Say I'm a casual shopper on Amazon. I'm into historical horror novels involving supernatural activity (don't judge), so I type historical, horror and ghosts. Maybe I like Civil War ghost novels in particular, so I add Civil War. If you don't have any of these tags (or any tags at all) I'm not going to find your book.
Maybe you don't care, since you've never written a story set in the Civil War about the ghost of a Roman general and a runaway war bride, but one day I might go searching for books that are much closer to your genre. My taste is eclectic.
So before you publish, write your tags. Think about the words that you would use to describe your book, and make yourself a little list. Don't forget to include all genres that fit, your own name, and indie (if you're an indie). If your story has vampires or werewolves or any other interesting non-humanoids, add them as tags. Don't forget about synonyms. I like to tag teen as well as young adult, because they mean the same thing. So if you're writing murder mysteries, you might want to use tags like murder, killer and death.
Now think of two- and three-word phrases that can be used to describe your book. Tags don't have to be just one word, and shouldn't be. You still want me to find you if I type murder mystery or female detective. So add phrases to your tag list, as well. In some cases, websites will limit the amount of tags you can add. Circle the top 5 on your list -- the words and phrases you believe describe your book most accurately -- and use these first.
Tagging your books makes them easier to find...and that's the goal. So get to tagging everywhere you can, and take that one extra step before you self-publish.