DTD (Document Type Definition)

A Document Type Definition (DTD) is a set of rules that defines the structure and elements of an XML document. It specifies what tags are allowed, how they can be nested, and the types of data that can be included. Think of it as a blueprint or a contract that ensures the data is organized consistently, making it easier for programs to read and process the information. DTDs help maintain data integrity and enable different systems to communicate effectively by adhering to a common format.