Categories vs. Tags

Originally published on WordPress.com
Categories vs. Tags_2
Once upon a time, WordPress.com only provided a Category option.
Categories allowed for a broad grouping of post topics, but when you wanted to describe a post in more specific terms, more categories were required. That led to very long category lists inside the blog and very long lists in Categories Widgets.
So we now have tags, too.
Tags are similar to categories, but they are generally used to describe your post in more detail.
For example:
Categories vs. Tags
Frequently Asked Questions
We understand that it may be a bit confusing upon first glance (especially to new bloggers), so here are some common questions and answers that may help you out.
Do I have to use tags?
The use of tags is entirely optional (although each post must be attached to at least one category).
Are categories and tags hierarchical?
Categories can be arranged in a hierarchy (see the categories widget to learn more). Tags, however, exist in their own right and have no set relationship to anything else.
Is Tag the same as tag ?
Yes. Capital letters do not change a tag. Blogging is the same as blogging.
Is there a limit to the number of tags I can have?
Yes, the sky. In other words, no.
Is there any advantage to using tags or categories, or both?
Your posts will appear in the Topics listings of any tags or categories you use. Therefore, assigning tags and categories to your post increases the chance that other WordPress.com users will see your content.
However, you don’t want irrelevant content showing up on the topics listings or search, and neither do we. That’s why we limit the number of tags that can be used on a public tag listing. Five to 15 tags (or categories, or a combination of the two) is a good number to add to each of your posts. The more tags you use, the less likely it is that your post will be selected for inclusion in the topics listings.
Why aren’t my posts showing up on the Topics pages?
Check out the Topics documentation.
How are the archive URLs different for tags and categories?
If you publish a post attached to a category “food,” the URL will look like this:
The same post using the tag “food” will look like this:
If you publish a post attached to a category “food” and with the tag “rice”, the URLs will look like this: