HTML Doctype declaration
This is good practice for HTML documents that start with a <!DOCTYPE> declaration. The HTML <!DOCTYPE> is used to define which version of HTML the document is using .The DTD stand for document type declaration
<!DOCTYPE> tag is an information to the browser about what document type to expect.
Suggestion − The <!DOCTYPE> is an empty tag that does not have an end tag!.
Example for HTML Doctype declaration
<title>This is Doctype example</title>
All web page content.
In HTML5 there is only one declaration i.e.