When creating content, writers use H1, H2, etc. to design headings for each page. When writing your headings, it is important to be concise in the wording. If you have a 2 keyword phrase and the heading is 10 words long, your keyword phrase only makes up about 20% of the total verbiage. If you have a 4-word heading on the other hand you would then have a 50% density and increased priority given to the keyword phrase you are targeting.