Definition
Schema markup is the implementation of Schema.org vocabulary on web pages to provide search engines and AI systems with explicit, structured descriptions of page content. Schema.org defines hundreds of types (Organization, Article, Product, FAQPage, HowTo, Review) and properties; markup is typically deployed as JSON-LD, though Microdata and RDFa are also valid. For GEO, schema markup serves two functions: it triggers rich results in traditional search (which can feed into AI retrieval pools), and it provides AI engines with high-confidence entity and content signals. Not all schema types matter equally for AI visibility — prioritize Organization (brand identity), Article (content metadata), FAQPage (direct question-answer pairs), and Product (specifications) over decorative types like BreadcrumbList. The key quality check is truthfulness: schema markup that contradicts visible page content (inflated ratings, unearned review counts, fabricated authorship) is penalized by Google and treated as a negative trust signal by AI engines.