The HTML document heading is basically an element of the document. This element contains all information about the document or the text. The very element below the HTML element is the heading or head.
The element can also be referred to as a container to all the information and body of the HTML document. It is much like a title element but the title appears on the title bar of the main window:
In the above figure, Title is what the document is about and is written on the title bar and on the tab button. The title element is displayed apart from the text or the document. In short we can say that a title has nothing to do with the text all its function is only to be displayed on the title bar and tell the reader what the document is about.
In the body of the HTML document, first element is H1 as shown above. H1 can also be considered as the heading number 1 that is on the top of the HTML document. There are also other types of heads that relates two documents.
As described earlier, we can only write 6 headings in a document. Six heading means the level of headings like level 1 heading is at the top next is level 2 and vice versa. H1 means that the text written in between this tag will have the highest level and H6 will be at the lower point.
The headings can be further modified that is we can boldface, italic or underline the headings, and can also justify the headings for example left justified, right justified, centre, etc.
Different browsers take same elements in different ways. But the HTML hypertext specifies the logical structure irrespective to the physical layout that includes highlighting, boldfacing etc.