# content
It can be difficult to understand the role of JSON-LD in #ActivityPub. I see criticisms that are based on the belief that JSON-LD is a schema language or a validation tool. It's not. It's an RDF serialization. There's a good online book, "Validating RDF" that discusses several tools (including JSON Schema) that can be used to constrain message shapes (define schema) and do validation based on those constraints.
http://book.validatingrdf.com/index.h tml

# contentMap.en
It can be difficult to understand the role of JSON-LD in #ActivityPub. I see criticisms that are based on the belief that JSON-LD is a schema language or a validation tool. It's not. It's an RDF serialization. There's a good online book, "Validating RDF" that discusses several tools (including JSON Schema) that can be used to constrain message shapes (define schema) and do validation based on those constraints.
http://book.validatingrdf.com/index.h tml