Tags vs categories
In WordPress and most CMSs, categories are the main, broad sections of a site, and each post usually belongs to one of them. Tags are optional, more specific labels, and a post can have several. Categories give structure; tags connect related posts across categories.
Tags and SEO
Tag pages often do more harm than good for SEO:
- Many tags with only one or two posts create thin, near-duplicate archive pages.
- Similar tags, such as “SEO tips” and “SEO tip”, compete with each other and with your real pages.
Use a small, planned set of tags, each with enough posts to make its archive page useful, or set tag archives to noindex. Merge or remove tags that are rarely used.