One of the most discussed topics we see when attending WordCamps and other events is what’s better for SEO: categories vs tags? What’s the difference between categories and tags? What’s the optimal number of WordPress categories? How many is too many? Is it okay to assign one post in multiple categories? Is there a limit of tags we can assign to each post? Do tags work like meta keywords? Are there any SEO advantage of using categories over tags or vice versa? We’ve seen quite a few commentaries on this subject through out the web, but we found that they were inconsistent and incomplete. If you ever had these questions, then hopefully they will be answered once you are done reading this post, so you can make adjustments to your blog if necessary.

Before we discuss any of the questions listed above, we need to understand what is categories and tags. In the WordPress nomenclature, both categories and tags are known as taxonomies. Their sole purpose is to sort your content to improve the usability of your site. Meaning when a user comes to your site, they can easily browse through your content by topic rather than browsing chronologically which is how blogs were initially setup.

What’s the difference between Categories and Tags?

Categories are meant for broad grouping of your posts. Think of these as general topics or the table of contents for your site. Categories are there to help identify what your blog is really about. It is to assist readers finding the right type of content on your site. Categories are hierarchical, so you can sub-categories.

Tags are meant to describe specific details of your posts. Think of these as your site’s index words. They are the micro-data that you can use to micro-categorize your content. Tags are not hierarchical.

For example if you have a personal blog where you write about your life. Your categories can be something like: Music, Food, Travel, Rambling, and Books. Now when you write a post about something that you ate, you will add it in the Food category. You can add tags like pizza, pasta, steak etc.

One of the biggest difference between tags and categories is that you MUST categorize your post. You are not required to add any tags. If you do not categorize your post, then it will be categorized under the “uncategorized” category. People often rename the uncategorized category to something like Other, ramblings etc.

Another difference is the way your category and tags permalinks (urls) look. If you are using a custom permalink (URL) structure, then your base prefix will look different. Example:

http://yoursite.com/category/food/

vs.

http://yoursite.com/tag/food/

What’s the optimal number of WordPress categories?

Up until WordPress 2.5, there was no built-in support for tags. This led to very long category lists because people were using it to define micro-details. Tags were added to improve the usability of your site. Having that said, we believe there is no specific optimal number of categories. The optimal number varies based on the complexity of your site. However, for the sake of structure and usability, it is best that you utilize sub-categories and tags.

Categories are meant to encompass a group of posts. It is always best to start with generic categories and work your way down with subcategories as your site grow. After having run multiple blogs, we have learnt that blogs evolve. There is no way that you can come up with all the right categories. Chances are when starting out, you are only writing one post a day. Or maybe 3-5 posts a day. Having 30 top categories is pointless specially when some of them will only have one or two posts. You are better off with 5 generic categories that have fresh content rather than 30 top categories where majority are not updated.

Let’s take a look at an example. Say that we are starting a social media blog in 2012. We want to share how-to tutorials, news, tools, case studies etc. We can create top categories like Twitter, Facebook, Google+, LinkedIn etc. As sub categories of each, we can have tools, how-to’s, case studies, news etc. However that is a very short-term mindset, and we will run into issues in the future. What if one of the social media network dies and a new one enters the game? You will be required to add yet another top level category and more sub-categories.

A much better way of structuring this social media blog would be to have top categories that are future-proof. You can have your categories like How-To’s, News, Case Studies, Tools, etc. But how would people know that it is about twitter? Well your categories are not suppose to do the entire job. This is where tags come in. Let’s say you wrote a how-to post about twitter, simply add the tag twitter. In your design just add a section called Popular Topics and control that manually with links to popular tags like Twitter, Facebook, Google+ etc.

When do you add Subcategories?

Let’s say that you do a case-study posts where sometimes you interviewed an expert for a specific case-study. Because there is no category called “expert interviews”, you will add that as a tag on that case-study post. If you find yourself doing a lot of interviews for case-studies and your expert interviews tag has 10+ posts in it and is consistently growing, then you should consider adding expert interviews as a sub-category of your main category “Case Studies”.

Yes, you will have to go back and edit your older posts. If your URL structure is /category/postname/, then you have make sure you are using the Redirection plugin. It automatically redirects your modified posts to their new URL, so you can keep all the search engine rankings.

Do I have to use sub-categories?

No ofcourse not. You can always leave popular tags as tags. In our example above, almost all posts will have a tag for a specific social media network like twitter, facebook, etc. But we are not creating those as categories. The only reason why you add sub-categories is to make it easy for your users to find the content. You are more than welcome to simply add the Expert Interviews tag in your site somewhere.

Remember the whole purpose of categories and tags are to make it easy for your users to browse your site.

Is it okay to assign one post to multiple categories?

You might read on other sites that assigning posts to multiple categories can hurt your SEO. Some say that you can get penalized with duplicate content because of that. We believe that statement is not entirely true. First of all, don’t get lost with SEO. Remember the purpose of sorting your content efficiently is to help users find it. By the nature of how top categories should be setup, you shouldn’t be able to classify one post into multiple top-level categories. For example, if your blog has three categories “Advertising, Marketing, and SEO”. Your posts often tend to fall into multiple categories. Perhaps you need an umbrella category for all three? Maybe they should all fall under Business? Or you can have one category called Advertising & Marketing. Then have SEO as a sub-category for those.

There is no SEO benefits to adding multiple categories. If you think it helps your users, then you are more than welcome to add one post into multiple categories. However, if you see this becoming a regular issue, then you should consider restructuring your categories. Maybe some of your categories need to be tags. Or maybe they should be subcategories of one major category. It is mainly about making the user experience better.

If you are super concerned about duplicate content penalty, then simply (noindex, follow) your category taxonomy using the WordPress SEO by Yoast plugin.

If you only want to (noindex, follow) specific categories, then you can do so by editing the category themselves. Yoast plugin has the setting to override the global settings.

Basically when you (noindex, follow) certain thing, it tells Google and other search engine bots to follow all post links in these categories, so all posts can be indexed. However do not index the main category archives to prevent duplicate content.

Short answer: WordPress allows you to add one post into as many categories as you like. Yes it is okay to assign one post into multiple categories as long as you think it helps your users. However, if you think of categories as Table of Contents for your blog where posts are chapters, then can you have one chapter in two separate sections? The answer to that question is NO.

Is there a limit of tags we can assign to each post?

Short answer to this question is NO. WordPress has NO limits on the number of tags you can assign to a specific post. You can add 1000+ tags if you like. However, the purpose of tags is to relate your posts together. Again think of tags as the index or your book. These are popular keywords that you can use to loosely relate your posts. This makes it easy for users to find your posts specially when they are using the WordPress search. It also helps if you are utilizing the tag archive for users. We say add no more than 10 tags to your posts unless you can justify it. For example: if you are running a movie review blog, you may add multiple tags: actor/actress names (this alone can be over 10). But chances are that you may review multiple movies that have Adam Sandler in it. But for other simpler scenarios, you should really limit the amount of tags you use. Otherwise, you may find yourself with over 10000+ tags with only 300 posts on the site.

Do tags work like meta keywords?

Often people mistake tags to be like meta keywords for your blogs. This is the main reason why they try to add as many tags as possible. Tags are NOT meta keywords for your blog. At least not by default. Popular plugins like WordPress SEO by Yoast allows you to use your tag values to be in the meta keywords template. But if you don’t have these plugins configured to do that, then your tags DO NOT work like meta keywords.

Categories vs Tags: What’s better for SEO?

The most asked question that we see being asked on this topic is: Are there any SEO advantage of using categories over tags or vice versa? The simple answer to this is NO. You should NOT look at this as categories or taxonomies. They are meant to work together. If you have read this post, then you should be able to understand the individual purpose of categories and tags as well as their combined purpose for your site’s usability.

Conclusion

Your site is about your users not search engine bots. The goal of every search engine is to think the way users think when valuing your content. If you make your decisions based on usability, you will almost always find yourself reaping the SEO benefits. Categories and Tags are just the two default taxonomies that comes with WordPress. Most advanced sites use custom taxonomies for sorting their content alongside with categories and tags. Think of your blog as an ever evolving book. Choose the Table of Content (categories) wisely. Make sure that they are broad topics, but be cautious to not make it too vague. Use tags to loosely relate multiple posts. If you see a certain tag is becoming popular, then consider adding it as a sub-category. However, if you have to add the tag as subcategory of multiple top-level categories, then leave it as a tag. The goal is always to make the site as user friendly as possible.

We hope that this article helps clear any and all confusion when it comes to the topic of categories vs tags. We would love to hear your thoughts on this matter. How do you sort your content? what best practices do you follow?