AI visibility has four layers: access (are AI crawlers allowed in?), readability (is key content in server-rendered HTML?), understanding (do schema and plain-language copy make the site's identity unambiguous?), and citation (do engines actually reference the site in answers?).
It is measured two ways: technical readiness audits that score the first three layers, and citation tracking that samples real prompts to measure the fourth. Both matter — readiness without citations means work to do; citations without readiness is luck that won't scale.