What is the difference between JSON-LD, Microdata, Schema, and Structured Data?

Despite being inherently different, the terms microdata, schema, structured data, and JSON-LD are used interchangeably within the context of SchemaPlus.

To start off, schema is a set of properties that defines an entity. These properties are put into schema vocabularies that’re set out by Schema.org. Schema.org vocabularies are created explicitly by developers to translate their websites’ content into a more comprehensible search engine language. However, search engines read those vocabularies only if they are written in an appropriate format which is what JSON-LD is.

Search engines need to understand the language in which schema is written, i.e. its code format. JSON-LD is the code format that not only helps search engines read schema vocabularies but is considered to be the most preferred and easy-to-read for search engines today.