HTML or HyperText Markup Language is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScript.
Web browsers receive HTML documents from a web server or from local storage and render the documents into multimedia web pages. HTML describes the structure of a web page semantically and originally included cues for the appearance of the document.
doctype, which is short for “Document Type Declaration”. The doctype declaration should be the very first thing in your HTML document, before the tag. The doctype declaration is not an HTML tag; it is an instruction to the web browser about what version of HTML the page is written in.
In its simplest form, a doctype declaration looks like this:
The doctype declaration is not case sensitive. However, for historical reasons, all major browsers treat it as if it were in uppercase. Therefore, always use uppercase letters for this element! Spaces are also not allowed in the doctype declaration. The doctype declaration must always contain just one exclamation point, even though there are many different types of !DOCTYPE declarations (see below). If your Doctype Declaration doesn’t look exactly like this example, don’t worry – there are many different types that we’ll discuss later on in this article. For now, just remember to use .
The Doctype Declaration refers to which version of (X)HTML you are using in your document. There are many different versions of (X)HTML – each with its own set of rules that you must follow when coding your pages.
(X)HTML 1.0 was released in 2000 and was the first true (X)HTML standard – before that there were many versions of HTML, but no real standard that everyone agreed on).
There are three main types of (X)HTML:
1. Strict: This is a well-formed markup which contains only those features which comply with World Wide Web Consortium specifications and recommendations;
2. Transitional: This allows deprecated features from earlier versions of HTML;
3. Frameset: This is used only when frames are required within a document
So how do you know which Doctype Declaration to use? Well, that depends on what version of (X)HTML you’re using…
