The skeleton of a page.
WHAT EVERY DOCUMENT NEEDS
A declaration of the document type A root element, with the language declared A head, containing information about the document A body, containing what is displayed
WHY DECLARE THE LANGUAGE
Screen readers use it to pronounce content correctly, and translation tools use it to identify the source.
WHAT BELONGS IN THE HEAD
The character encoding The title The viewport setting Descriptions and metadata Links to stylesheets
WHY THE ENCODING FIRST
It must be declared early, or the browser may begin interpreting bytes incorrectly.
WHAT TO ALWAYS USE
The international standard encoding, which covers every writing system.
WHAT THE TITLE DOES
Names the document in the browser, in bookmarks and in search results.
WHAT THE VIEWPORT SETTING DOES
Tells mobile browsers to use the device width rather than pretending to be a desktop.
WHAT HAPPENS WITHOUT IT
The page renders as a shrunken desktop layout, unreadable on a phone.
WHAT TO CHECK IN EVERY DOCUMENT
That all four of those are present and correct.
