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).
With value attribute, you can set a default value for your text box. 1  HTML stands for Hyper Text Markup Language. 2  HTML is a markup language. 3  A markup language is a set of markup tags. 4  The tags describe document content. 5  HTML documents contain HTML tags and plain text. 6  HTML documents are also called web pages.