Each site is allocated a crawl budget by search engines, put basically this is the amount of “bots” that can visit your site in a set amount of time.
As a blogger we want the bots to visit our posts and important pages but to ignore those pages that aren’t really useful or provide little value to help us improve our ranking.
So categories and tags which can often have duplicate content to another one and when we have 1000s can really dilute the “bots” crawls around our site.
To prevent them going to URLs that have little value we can no index them. This means we tell the bots that this page isn’t to be included in the crawls.
Your crawl budget then goes to the most useful pages and posts where you want google to show you in a search.
Because tags are your “index” for your posts then as there is likely to be lots of cross over and 1000s of tags for a blog with history then these are best noindexed.
Categories where you often put posts in multiple categories should be noindexed. If however, a post will only ever go into 1 category on your blog then this is when they should be indexed.
If you are on blogger this is already in place so no changes needed. If you are WordPress hosted then you can add in YOAST when you have a Business Plan but in a self hosted wordpress site YOAST is the best plugin to do this with and if you join us for office hours this week (or watch the recording) I’ll be going over how to set up YOAST with you.