An entity type is a category of entities that share certain characteristics or properties. In JSON-LD, entity types are represented using types, which are used to specify the class or category to which an entity belongs. For example, a person entity might have a type of "Person", while a product entity might have a type of "Product". Entity types allow you to specify the nature of an entity and define how it should be interpreted within the context of your JSON-LD code An entity type is the fundamental building block for describing the structure of data on your page, each type has to have a unique name, unique ID, informational data in the form of properties, and relationship data in form url There are many languages that are recommended to describe entities on the web such as Web Ontology Language OWL, XML, RDF but the most common one is JSON-LD from Schema.org it has around 1,400 entity types and their properties, examples are: Organization, LocalBusiness, Product, Service, Article etc. schema.org describes a variety of other item types, each of which has its own set of properties that can be used to describe the entity Schema.org has a set of types, arranged in a multiple inheritance hierarchy where each type may be a subclass of multiple types, for example, a jewelry shop is a subclass of a store which is a subclass of a local business, and a local business is a subclass of organization