E-E-A-T stands for experience, expertise, authoritativeness and trustworthiness, the qualities Google's quality raters look for when judging whether content is helpful and reliable.
Two clinic pages explain knee replacement. One is unsigned and generic. The other names the surgeon, states their registration and years of practice, describes the procedure from first-hand cases and lists the clinic's address and phone. The second shows far more E-E-A-T signals a reader, and a rater, can check.
E-E-A-T is not a score and not a ranking factor you can switch on. It is a framework from Google's guidance for how people, including its quality raters, judge whether a page deserves trust. Google says trust is the most important of the four, and that the stakes rise for topics that could affect health, money or safety.
For a clinic, school or financial service, that means your pages are compared with a high bar. For a restaurant or a D2C brand the bar is lower, but a reader still decides in seconds whether you seem real.