H1, h2, h3
The h1, h2s, and h3s are the titles and secondary titles of a page, also known as H tags. These tags are used to communicate to Google the primary focus of a page, and the secondary or tertiary focus of a page. These H tags can be used to send a strong signal to Google, and to help the visitor understand the page. There are rules regarding how these should be implemented, how often, and in what fashion. When those rules are ignored, problems are created.