Comments and comments were originally an excellent way for webmasters to build community and readership. What’s annoying is that the comments and comments features are often abused by spammers or other bad-minded people, many of whom use scripts or other software to generate and post spam comments.
If too many such spam messages are left, it will not only affect the beauty, but will also in most cases bring negative impacts on your website the search engine's power reduction! This also makes many webmasters restrict the publication of URL hyperlinks in comments or messages, but this makes it impossible to reply to some content that really needs link-oriented.
Now we can use nofollow tags. A few years ago, major search engines such as Google, Yahoo! and MSN introduced nofollow, and this attribute has been widely adopted. No links that use the rel=nofollow attribute are used to calculate PageRank or determine the relevance of your page to user queries.
For example, if the spammer adds a link like this to your comment:
<a href=https://www.VeVb.com/>This is a good website! </a>It will convert to:
<a href=https://www.VeVb.com/ rel=nofollow>This is a good website! </a>This new link will not be considered when calculating PageRank.
In this way, problems can be avoided when passing PageRank. Although spam and comments cannot be avoided, meaningful guided links can still be posted normally!
By default, many blog sites (such as Blogger) automatically add this property to all posting comments.