Lot of bloggers are not sure on whether they should allow search engines to index their wordpress tags and categories. Most of the SEOs or experts will ask you to play safe and recommend not indexing these but I have seen top blogs allow Google to index their tags and categories. Doing a search on Google.com with site:www.site.com/tag and site:www.site.com/category can show you whether the site is allowing Google to index it’s tags and categories.
I personally feel that there is no set rule which asks you to allow indexation of tags and categories. It depends on the blog owner on what he prefers. Of course, there are some advantages and some disadvantages of indexing your tags and categories. As a blog owner, one should always see how such things affects the user behavior on your site. As far as the big G is concerned, Google always tells us to make sites as user friendly as possible. This automatically means that the more easier it is for your site visitor, the chances are that Google is going to like your website more.
Advantages of Indexing WordPress Tags and Categories:
More results in search : Allowing search engines to index your tags and categories means you will have more pages in search engines results. This can be helpful only if a particular page on your site is ranking only because of it’s tag or category. I’ve never seen this happen to my site. I always see my main page listed right below the tag page in search results. But if it’s happening for you then you may keep it that way for your benefit.
Usage of additional keywords: At times your article or blog post might not have enough keywords you want to target. You want people to reach your post using those keywords or key phrases as the information is right there. Using those keywords in tags or categories can help you rank on relevant keywords.
Disadvantages of Indexing WordPress Tags and Categories:
Duplicate Meta Descriptions: The biggest problem with the tag and category pages is that it pulls the meta description from the top post on that page. Google doesn’t seem to like this and the search engine bot will see two different pages with same information. There is a risk of Google devaluing one of the pages here which might not be good for your website. In this case, if your main content page is devalued then your competitor might just get an edge as he will be competing with your ‘low value’ or ‘no content’ tag/category page and not your actual content page.
User behaviour: We always want our site visitors to use less number of mouse clicks to reach their final destination. When a visitor reaches the tags or categories page, He will have to click one more time to reach the final destination in order to read the entire post or even make that sale for you. This can work negatively for you and your website. Some visitors might have no clue on where they have reached and might just go away from your website.
Conclusion: These are the two main advantages and disadvantages that I personally have experienced with indexation of tags and categories. I personally do not allow tags and categories to be indexed because it makes no sense showing pages to people which won’t be of any use to them. Developing and optimizing websites and blogs just for search engines is never a good idea according to me. If you are really not sure on what to do, I would recommend some testing and seeing the results for yourselves. This kind of testing might take lot of time because indexing and de-indexing in Google SERPS can take months.
If you are really not bothered about sales, conversions or no. of visitor clicks, I would recommend you to allow indexation of tags and categories. Just make sure that all your tags and categories have a unique meta description. This can be a real pain if your site is too big. Also, this might raise a flag and Google might start devaluing your pages. I would never want my tags and category pages ranking above my real content pages. They might bring in a few clicks to my website but the main question is will they add any value to my site visitors?