‘H1’ stands for ‘Heading 1’ – simply put this is the main heading of the page.
All web pages are structured with a hierarchy that search engines read through in order to draw the correct information and link their users accordingly. By making something an ‘H1’ you are telling search engines that this piece of text, or heading, is the most important part of the text and to read it first.
It is important to note that H1 isn’t the only heading tag available. Headings within HTML go from H1 – H6 and the lower the number the higher the rank. So if I had a subheading within my page I could use an ‘H2 Tag’ or ‘H3 Tag’ to show that it is still more important than the other text content, but not as important as the ‘H1’.
Six ex-NoW journalists held over phone hacking