<!DOCTYPE> element indicates in which standard to display the current page.
This element is indicated at the very beginning of the HTML code. Comments should also go after the definition of
There are several types of
<!DOCTYPE>, but in the modern standard HTML 5 is used as in the code below:
<!DOCTYPE html> <html> <!-- page code --> </html>
<!DOCTYPE> is not specified, the browser will display the page in compatibility mode (quirk mode), i.e. according to the old html standard. This mode is necessary for compatibility of old browsers.