Referring domain
Also called linking domain, linking root domain
A distinct website that links to a domain at least once, counted once no matter how many individual links it carries. It is the more meaningful of the two link counts, because signal saturates quickly per source.
If you watch one link number, watch this one.
Search engines discount repeated links from the same source steeply. The first link from a site carries most of whatever signal that site can pass; the thousandth carries almost none. Counting referring domains rather than links approximates that behaviour without pretending to model it.
The ratio is diagnostic. A domain with 40,000 backlinks from 90 referring domains has a footer or a widget somewhere. A domain with 900 backlinks from 600 referring domains has been linked to by six hundred separate people. The second profile is far stronger and far smaller.
Growth rate reads better than total. Ten new referring domains a month, sustained, is a healthier signal than a one-off spike of four hundred, which is more often a syndication event or a directory dump than a change in how the web regards you.
netweft reports referring domains as its own lookup, priced per request, beside the link summary and the individual links.
Last reviewed . Also served as markdown at /glossary/referring-domain.md.