Probably the most important part of HTML is the compulsory tags for, as the name implies, the code will break if they are not used correctly.
<!DOCTYPE html> is the first compulsory tag. It is an instruction to the browser being used regarding the type of HTML in use.
<html> is the second compulsory tag. It tells the browser that the code is in HTML and contains the other tags. It must be closed.
<head> is the third compulsory tag. It contains the code that does not appear on the screen (apart from the title). It must be closed.
<title> is the fourth compulsory tag. It contains the text that will appear in the title of the tab. It must be closed.
<body> is the fifth compulsory tag. It contains everything visible in the main body of your tab. It must be closed.
