What does DOCTYPE mean?

Question

can anyone give This answer doctype is what

Answer 1

A document type declaration, or DOCTYPE, is an instruction that associates a particular SGML or XML document (for example, a webpage) with a document type definition (DTD) (for example, the formal definition of a particular version of HTML1.0 - HTML 4.0). In the serialized form of the document, it manifests as a short string of markup that conforms to a particular syntax.

https://en.m.wikipedia.org/wiki/Document_type_declaration

Answer 2

It declares the document.