I covered how to use the broader idea of categories for your blog posts in this article.
Now, I’d like to contrast that a bit with the use of tags. To me (being a book indexer), tags are more like an index than a table of contents. Unlike a book index, though, tags don’t have to be in alphabetical order or in a list at all; they can be unordered because they are accessible by using a search tool. The computer doesn’t need all the terms in order to complete the search quickly for you. One of the advantages of computers over humans is their ability to use “brute force” to find terms, where we humans need an ordered list to scan.
On the other hand, the computer can’t always tell which mentions of a term are important enough to give you results for, so human indexers continue to create value by choosing significant topics for indexes. Search engines and indexes can actually complement each other.
But I digress. 🙂 Tags in your posts allow folks to use the search feature on your site (I do hope you have one) to find any articles that mention book titles or people’s names, or specific subjects that aren’t part of the site’s categories.
In the spirit of good book indexing (and to keep search engines like Google’s from downgrading your site), though, you don’t want to just tag every noun in your post, or even get carried away with more than, say six, tags for a post. Google has definitely taken to downgrading sites that use tags unrelated to content at all, and I know you all won’t be trying to play that game. But even with subjects and names that are in or related to your post, keep your tags restricted to names and subjects that you spend some verbiage discussing. For example, just because Bill Gates shows up in your post on how to use Microsoft Windows 10 doesn’t mean his name should be in your list of tags. If you were writing about the Gates’s education foundation, then his name might be appropriate as a tag. It’s all about what we indexers call “significance.” Do your blog readers a favor and make the quality of your site better for Google by sticking to the few most relevant terms for each post.
In this age of information overload, quality of information is of crucial importance; be a purveyor of quality. 🙂