"rel" attribute in the link - "nofollow" vs "ugc"

Question

In Google's SEO guide, they say this:

To tell Google not to follow or pass your page's reputation to the pages linked, set the value of the rel attribute of a link to nofollow or ugc.

I could not find ugc as a value in the w3schools or MDN Docs. What is the ugc and when I should use it instead of nofollow?

Answer 1

It is used for user-generated content (ugc), such as comments and forum posts. I found this in another Google Docs:

rel="ugc"

We recommend marking user-generated content (UGC) links, such as comments and forum posts, with the ugc value. When would this be useful? If your site has a blog with public commenting turned on, links within those comments could pass your reputation to pages that you may not be comfortable vouching for. Blog comment areas on pages are highly susceptible to comment spam. Nofollowing these user-added links ensures that you're not giving your page's hard-earned reputation to a spammy site.