Domain trust reflects how credible and reliable a search engine considers your website overall. There's no single public score for it; instead it's an aggregate impression built from the quality of your backlinks, the site's history, content accuracy, security, and how closely it aligns with the expertise signals search engines value.
Authority is roughly about influence and link strength; trust is about whether that influence was earned honestly. A site can accumulate authority-style metrics through aggressive link building yet score low on trust because its link profile looks manipulated or its content is thin. Trust is what keeps a site standing through spam and quality updates, where domain popularity alone won't save it.
Two health blogs publish near-identical articles on the same day. The three-year-old site with citations to medical bodies and links from health publications ranks first; the six-month-old site with anonymous authorship and a handful of forum links barely appears. Same words, different trust — and trust is what tips the result. Building it is the long game behind effective off-page SEO.