What is DOCTYPE in HTML? Why do we use it?

What does the tag DOCTYPE in HTML code do to the browser? Why do we need to include it in every webpage we create? What happens without it?

When we sit down to write an html document, one of the first line of code we write is <!DOCTYPE html>. But what does this line do? What is significance of this line to a web browser? What happens if we miss including the DOCTYPE tag? Is it even a tag in the first place? We will answer these questions in this article.

What is DOCTYPE in HTML?

DOCTYPE is a type of directive that tells our web browser what type of document it is dealing with. As there are multiple versions of HTML documents that a web browser need to deal with, each following a different version of HTML definition standards or non HTML documents such as XML files, mentioning the “type” of this particular document helps a web browser to decide and adjust itself to render the specified document appropriately.

What happens if the DOCTYPE is not mentioned in an HTML document?

Specifying the DOCTYPE of a document will help a web browser to make appropriate decisions in rendering that file to its user successfully. In the event a web document does not have appropriate DOCTYPE specified, the web browser will try to make a best guess and try to render the document accordingly. However, a result of this could be that the rendering might not be happening in the most optimal way and as a result, some of the documents might not get rendered properly.

Is DOCTYPE even a HTML tag?

Actually, No! 😮

DOCTYPE according to HTML specification is not a HTML tag, but a declaration for the browser to make use of.

Does DOCTYPE have an end tag?

The answer is NO. DOCTYPE is not a HTML tag and does not have an explicit end tag to itself.

In the earlier days, web documents used DOCTYPE declaration effectively to let the browser know what type of HTML standard specification the document was following. As a result, the first line of a web page that declared the DOCTYPE had a very lengthy string to it, something like this:


But these days, with most of the websites using HTML 5 specification, the actual usage of DOCTYPE has become more or less redundant and hence we can get away by just declaring the DOCTYPE as:

<!DOCTYPE html>

and browser will still be able to handle it perfectly.

Hope this gave a bit of clarity on some of the doubts you had around DOCTYPE declaration in HTML. If you have an inputs or queries regarding it, don’t hesitate to ask about it in the comment section below!

Until then, Happy Coding!

By Amar Nath

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