What is a subheading and how do they help determine the structure of the text in this article?

A subheading are mini-headlines and play a huge role in capturing readers attention. It also keeps them moving down the page from one subhead to the next. Subheadings are smaller than the main headline but larger than the rest of the text in an article. They're meant to stand out in an article. (Also there's no article in the question below).