"nofollow" means not to pass weight and provides a way for webmasters to tell search engines "Do not follow the link on this page" or "Do not follow this specific link" .
Form of nofllow
1.
Page-level meta tag
2. sign in
Link level attribute
When to use nofollow
1. Untrustworthy content
2. Paid links
3. Crawl according to priority
4. Customer service QQ on the webpage
The role of SEO optimization
1. Prevent directing garbage Website
2. Concentrated weight