Backlink

Backlinks are one of the oldest signals in search. They still matter, but not every link counts the same way. This entry covers link quality, the rel attributes, and popular metrics that Google does not use.

Backlink vs referring domain

A backlink is one link. A referring domain is one website that links to you. A site can send you hundreds of backlinks and still be a single referring domain.

That difference matters when reading reports. A directory that links from every page of its sidebar can add 500 backlinks overnight. It is still one site vouching for you once.

Domain Authority and Domain Rating are not Google metrics

Domain Authority comes from Moz. Domain Rating comes from Ahrefs. Each tool estimates link strength with its own model. Google does not use either score.

Google made this clearer in June 2026. Its new guidance on third-party SEO tools says those tools lack access to Google’s internal ranking data. Use DA or DR to compare sites roughly, never as a target.

The rel attributes

When a site links to you, it can add a rel value that changes how Google treats the link:

• rel="sponsored" marks paid links and ads. Google prefers it for paid placements.
• rel="ugc" marks user-generated content, like comments and forum posts.
• rel="nofollow" is for other links the site does not want to vouch for.

Google says links with these values are generally not followed. A nofollow link can still bring real visitors, though.

Good backlinks come from relevant sites, sit inside real content, and would exist even without SEO. Google’s link spam policy covers links made mainly to manipulate rankings. Examples include buying links that pass ranking credit and excessive link exchanges. Link building is fine when it earns links. It turns risky when it manufactures them.

Example

A Bacolod pasalubong shop pays ₱2,000 for a link on a blog network. The link has no rel attribute. Meanwhile, a local news site covers the shop’s piaya festival booth and links to it naturally. The news link is the one worth having. The paid link should carry rel=“sponsored” or be removed.

For hands-on practice judging which links are worth chasing, go to the linked lesson.