In biology, cell theory is a scientific theory which describes the properties of cells. These cells are the basic unit of structure in all organisms and also the basic unit of reproduction.
The doctype declaration should be the very first thing in an HTML document, before the <html> tag. The doctype declaration is not an HTML tag; it is an instruction to the web browser about what version of the markup language the page is written in. The doctype declaration refers to a Document Type Definition (DTD).
[MS-DOCX]: Word Extensions to the Office Open XML (.docx) File Format. Specifies the Word Extensions to the Office Open XML File Format, which includes elements and attributes that extend the XML vocabulary for representing word processing documents as presented in the ISO/IEC-29500 specification. This page and associated content may be updated frequently.