Document Type Definition (DTD)

A Document Type Definition (DTD) is a set of rules that defines the structure and legal elements of an XML document. Think of it as a blueprint that specifies what tags can be used, how they can nest, and what attributes they can have. By adhering to a DTD, XML documents can ensure consistency and facilitate data sharing among different systems. It helps both computers and humans understand the data's organization, making it easier to validate and process the information contained within the document.