Schema.org is a collaborative vocabulary, founded by Google, Bing, Yahoo, and Yandex in 2011, that defines a shared set of types and properties for marking up structured data on web pages. By adding Schema.org markup, you tell search engines what your content represents — a recipe, a product, an event, a person — rather than leaving them to guess. The markup is most commonly implemented using [JSON-LD](/glossary/json-ld).