Schema.org is the shared structured-data vocabulary used by Google, Bing, Yandex, ChatGPT, Perplexity, Claude, and most major search and AI engines. Founded in 2011 by the major search companies, it provides a single hierarchy of types (Article, Product, FAQPage, HowTo, Organization, WebSite, and more) that publishers embed in their pages via JSON-LD, Microdata, or RDFa.
For AEO specifically, schema does not directly raise your ranking. Instead, it dramatically lowers the cost of extraction for AI engines. A FAQPage.mainEntity.acceptedAnswer.text field can be quoted verbatim by ChatGPT or Perplexity with a single structured-field read — no LLM reformulation pass required. Pages with FAQPage schema are cited 2-3x more often for question-type queries than equivalent prose without it.
The most impactful schema types for SaaS sites in 2026 are FAQPage (question-answer extraction), HowTo (step-by-step process extraction), Article (with author, datePublished, dateModified), Product or SoftwareApplication (for product pages), Organization (for site-wide identity), DefinedTerm (for glossary entries), and BreadcrumbList (for navigation hierarchy).
JSON-LD is the recommended format — easier to author, easier to keep in sync with the visible DOM, and the format Google's own documentation recommends. Critical rule: structured data must always describe content the user can actually see on the page. Schema that "invents" information the page does not show is treated as a manual-action risk by Google.