You may want to jazz up a page with eye catching headings or use bold or italics to emphasis certain words. All of those options are available to you in the editor.
There are six heading elements (h1 - h6). Google has recommended that each page have only one h1 heading. The title of each page is your h1. For example, for this page the h1 is "WordPress 101: Using Headings & Other Styles." With that in mind, you should only use h2 and below for your additional headings.
