Well, for starters, that list of Categories on the side (or bottom) widget of your site is rather like your Table of Contents, your “chapters.” These let you sort (categorize) posts into lumps of like content. Looking at the title of each Category will give you a good idea of how a blog is organized.
Enter “tags.” Tags then, in terms an author can relate to, are more like your Index. If a topic is in the index (tagged), it’s probably covered in more than one area of the book, but doesn’t require its own chapter (category).
So, because we’ve also tagged important words in posts, it’s easy to search for Facebook or Goodreads within our site and be taken to the list of posts that match that parameter. Tags are used to describe your post in more detail.
So, our categories provide a helpful way to group related posts together, and to quickly tell readers what a post is about. Tags help readers drill down to more specific information within a post.
Example: One of the categories in your thriller writing advice deals with natural disasters. Natural disasters is a great category. Now, you write a post on Hurricane Katrina. It would be in your Natural Disaster category, but you’d also tag that post hurricane katrina, so readers looking for specific information on that particular hurricane natural disaster can easily find your related content.
You may end up adding a category or two as your blog or author career grows. Example: Every time an author releases a new book its title will become a new category, so you can group all the news, reviews, upcoming events, etc. that you announce about that book.
The primary misuse of categories is in either A) having way too many, most of which should probably be tags or B) not bothering to categorize your post at all, in which case it will show as “Uncategorized” in its description. Like we tell clients, “No one searches the ‘net for uncategorized.”
Don’t use tags of words/keyword strings that don’t actually appear in your post. Meaning, if you write a post in your Great Musicians category, and it’s about Elvis, absolutely use Elvis as a tag. But if Elvis isn’t mentioned in the post, using the name as a tag, to mislead readers into being attracted to your post, is cheating.
Get caught and your ranking will suffer. Why? For the same reason we want to be able to search for great new kids toys for a young niece or nephew, and not be brought to a site selling little colored pills meant for an altogether other sort of play.