Nofollow
A link attribute that tells search engines not to pass ranking credit to the linked page.
Nofollow is a link attribute (rel="nofollow") that tells search engines not to pass PageRank (link equity) to the linked page. When you add nofollow to a link, you're essentially saying "I'm linking to this, but I don't want to vouch for it."
Originally introduced in 2005 to combat comment spam, nofollow is now used for any link you don't want to endorse: paid links, user-generated content, affiliate links, and links to untrusted sites.
In 2019, Google introduced two additional attributes: rel="sponsored" (for paid/sponsored links) and rel="ugc" (for user-generated content). Google also changed nofollow from a directive to a "hint" — meaning Google may choose to follow nofollow links for crawling and indexing purposes.
Using nofollow correctly is important for staying within Google's guidelines. If you're getting paid for a link (through sponsorships, ads, or affiliate programs), it should be nofollowed or marked as sponsored. Not doing so can result in manual penalties for both sites.
Why It Matters for SEO
Nofollow helps you link responsibly. It protects you from being penalized for linking to low-quality sites, and properly tagging paid links keeps you in compliance with Google's guidelines. Misusing nofollow (or not using it when required) can cause SEO problems.