Heading tags are commonly used to title different sections of a webpage.
Heading tags are important for SEO as the search engines pay special attention to text within these tags. Text within heading tags is seen as being more important.
You should use the differing degrees of heading tags logically according to their importance. For example the H1 tag - the most important tag - should go at the top of the page with your title. H2 tags should be used to head off main sections within the page and the H3 to H6 tags should be used for subsections thereafter.