Definition
schema.org is a collaborative vocabulary of entity types (Organization, Person, Article, Service, Product, FAQPage, HowTo, etc.) and their properties, maintained jointly by Google, Microsoft, Yahoo, and Yandex. It's the lingua franca for structured data.
Why it matters
Every schema-powered rich result, every LLM entity resolution, every knowledge-graph lookup traces back to schema.org types. Mastery of the vocabulary, which types fit which pages, is the difference between generic markup and markup that actually earns rich results.
How we think about it
We keep the schema.org spec bookmarked. When we add a new page type, the first question is 'which schema type fits?' not 'which template reuses?'. Our builders live in one file so the vocabulary stays internally consistent.