Well-formed XML means that the XML is correct (it has only one root node, and all elements match an end element tag)Valid XML means that the XML can be validated to an XML Schema or DTD, and that all the tags in the XML are also in the Schema or DTD, and in the right place.
If you use an xml tool like liquid xml studio or any other xml tool you will be able to convert your xml into an xsd or dtd.
DTD (Document Type Definition) is still used in legacy systems and older applications that have not yet migrated to newer alternatives like XML Schema or JSON Schema. It can also be found in some specific industries or domains that have standardized on DTDs for document validation.
xml stands for extensible markup language, xml is a markup language that is used to transfer data / information. Dtd stands for document type definitionand dtd is used to define the legal building blocks of an XML document.
XML Schema is an XML-based alternative to DTD.An XML schema describes the structure of an XML document.The XML Schema language is also referred to as XML Schema Definition (XSD).An XML schema is a description of a type of XML document, typically expressed in terms of constraints on the structure and content of documents of that type, above and beyond the basic syntactical constraints imposed by XML itself.
An xsd is used in an xml schema as a blueprint to define what can and cannot be included in an xml file.
An XML schema is a certain type of XML document. It is expressed in constraints, on top of the normal XML constraints, on the structure and content of documents of that type.
An xml is normally validated against an xml schema, the schema is the rulebook that defines what can and connot be included in your xml file. You can also use xml validation software which will check and validate your xml, that sit is correct in terms of syntax etc and then check it agianst yuour schema.
A Document Type Definition (DTD) is a set of markup declarations that define a document type for an SGML-family markup language (SGML, XML, HTML).A DTD uses a terse formal syntax that declares precisely which elements and references may appear where in the document of the particular type, and what the elements' contents and attributes are. A DTD can also declare entities which may be used in the instance document.
A DTD is the original type of XML schema. XML Schemas are used to formally describes the contents of an XML document. An XML schema describes the shape of the XML document, defining the data, sub elements or attributes it can contain, along with the number of times given entities can occur. A document type definition (DTD) is a set of markup declarations that define a document type for an SGML-family markup language (SGML, XML, HTML). A Document Type Definition (DTD) defines the legal building blocks of an XML document. It defines the document structure with a list of legal elements and attributes.
XML schema is used to define the structure, content, and data types within an XML document. It helps enforce rules for validating data in XML files, ensuring that they conform to a specific format. By using XML schema, developers can establish standards for data exchange and communication between different systems.
Currently, twelve different XML Schema languages exist. All twelve languages are used exclusively in XML Schema, which is a special kind of XML document. XML documents are documents formatted in a way that allows both humans and machines to understand easily.