What is the rel="nofollow" attribute?

The rel="nofollow" attribute is an HTML attribute used to instruct search engines not to follow or crawl a particular link. When a search engine encounters a link with the rel="nofollow" attribute, it will not pass any link equity (also known as PageRank) to the linked page, and it will not consider the link when determining the linked page's authority or relevance.

The rel="nofollow" attribute was introduced by Google in 2005 as a way for webmasters to indicate to search engines that certain links should not be considered as an endorsement or a vote of confidence for the linked page. This was primarily intended to combat spammy link schemes, such as paid links, comment spam, and link exchanges, which were being used to manipulate search engine rankings.

Webmasters typically use the rel="nofollow" attribute in the following scenarios:

1. **Paid Links**: When linking to a page for which payment has been exchanged, such as sponsored content or advertisements, to comply with search engine guidelines and avoid penalties for violating their terms of service.

2. **User-generated Content**: When allowing users to submit content with links, such as comments on blog posts or forum threads, to prevent spammy or low-quality links from affecting search engine rankings.

3. **Untrusted Links**: When linking to external websites that are untrusted or potentially harmful, to avoid passing any credibility or authority to those sites.

4. **Non-essential Links**: When linking to pages that are not relevant to the content or topic of the linking page, to avoid diluting the relevance of the page in search engine rankings.

It's important to note that while the rel="nofollow" attribute prevents the flow of link equity, it does not necessarily prevent search engines from discovering the linked page or indexing its content. Search engines may still crawl and index pages linked with rel="nofollow" attributes, but they will not pass any authority or relevance signals through those links.

Overall, the rel="nofollow" attribute is a tool that webmasters can use to control the flow of link equity and maintain the integrity of their website's linking profile.