Reference
Referring domain checker vocabulary, defined in a line or two
Eleven terms that appear in link reports and in our API, in alphabetical order, each tied to a source.
Link reports are full of near-synonyms. People mix up a backlink with a referring domain and a page with a site, and the mix-up changes the numbers by a factor of ten or more.
One big directory can hold 3,000 backlinks to you and still count as one referring domain. A referring domain checker counts each linking domain once, however many of its pages carry a link, while a backlink count adds every link separately. Mixing them up is routine.
Definitions below follow Google Search Central documentation where Google has a position and our API notes where we do.
Terms in alphabetical order
| Term | Definition | Note |
|---|---|---|
| Anchor text | The clickable words of a link | Rows are returned by the anchors action |
| Backlink | One link from a page on another site to yours | About 798.5 billion in our index |
| Dofollow | A link with no rel attribute that limits it | Not an official Google term |
| Domain Rating | 0-100 score from referring domains | See the formula entry |
| Nofollow | rel=nofollow, a hint that the link is not an endorsement | Google moved nofollow to a hint in March 2020 |
| Referring domain | A distinct domain with at least one link to the target | The input to DR |
| rel=sponsored | Marks paid or advertising links | Introduced by Google in September 2019 |
| rel=ugc | Marks user-generated content links | Introduced alongside sponsored |
| SpamBrain | Google's AI-based spam prevention system | Named in the December 2022 link spam update |
| Top pages | Pages on a site that attract the most links | toppages action, 2 credits |
| TLD breakdown | Linking domains grouped by extension | tld_breakdown action, 1 credit |
How the dates fit together
Link vocabulary changed in steps. Nofollow arrived in 2005 as a way to flag links that should not pass endorsement. Google added sponsored and ugc in September 2019.
Between 2005 and 2019 there was only nofollow. In March 2020 Google began treating all three attributes as hints rather than strict directives. Nofollow links, once ignored for ranking, may now be used. Older articles describe the old rule.
Penguin 4.0 in September 2016 and the December 2022 link spam update, which brought in SpamBrain, concern spam links and not the attributes themselves.
Three pairs that get confused
Backlink vs referring domain
One counts links, the other counts sources. Use referring domains when you want breadth.
Nofollow vs sponsored
Nofollow is generic. Sponsored says the link was paid for. Google treats both as hints.
Anchor vs title
Anchor text is on the linking page. A page title is on the target. The search action covers anchors, titles and URLs.
Quick answers
Is dofollow an official term?
No. Google documents nofollow, sponsored and ugc. A link with none of those is simply a normal link, and dofollow is trade shorthand for it.
Can one referring domain hold many backlinks?
Yes, and it is common. A sitewide footer link on a 5,000-page site is 5,000 backlinks from one referring domain, which DR counts once.
Which entry should I read after this one?
Read the API field entry if you plan to call the service, or the myth entry if you are weighing vendor scores.