Author's Organization of the Text
Chapter titles in informational texts usually prepare the student to understand the text.
Subtitles usually immediately follow the title and organize the information into sections. Titles and subtitles often provide the structure for an outline.
Headings usually begin a subsection after a subtitle. There are multiple headings for each section. They usually lay out the major points made by the author in each section.
Subheadings also help us understand the organization of the thoughts contained in the section, and the relationships of the parts.