Link attribute that shows a link is user-generated content (UGC). Used for comments, forum posts, or any other content sections where users can add content.| Ahrefs
Tag that tells Google not to take a link into account for ranking purposes.| Ahrefs
Site Explorer runs on a huge database of 35 trillion links and 651 million tracked keywords to give you the most complete SEO data about any website or URL| Ahrefs