This question really confused me. I am using since 2 years but not indexing and no follow to Google.
Lots of people searching about this I have found the good source about this I am going to share here.
If your website as a book then Categories should be Table of contents.
|How to use WordPress tags and categories|
and Tags are Index of your book.
WordPress Categories SEO
Categories help to better understand content both google and users, but it only sorts posts no additional info and customization. we can customize our category pages by adding content and meta description.
Now I am testing with creating a separate post for category adding some info for satisfying hungry google bot by adding additional content, And linking to posts.
So don’t try to block using robots.txt or meta tags.
Do follow, index tags,
WordPress tags optimization
Since, google banned meta keywords lots of SEO Gurus using tags as keywords in their websites. but no negative impact on those websites as thin, duplicate content.
Almost SEO blogger don’t index their categories and tags in google. rarely use tags.
DO NOT USE Tags as keywords.
SET do follow, no index
using Yoast SEO plugin
If you are writing about foods, you ate on your personal blog. categories should be Food, Music, Early Life Interest etc.
The post about what your eats. and category Food, and tags like pizza, burger, Roasted Chicken etc
Does google treat WordPress tags and categories as a duplicate content?
No, google officially announced on 2008, their system identifies that what is primary and secondary content. but now its 2015-16, google thin content penalty, manual actions are the little bit complicated.
Drive more traffic through tags and categories, may be 25-30%.
Archive pages:, Author Archive pages:, Format: these kinds of posts need to deindex or block.