End, to summarize what you are talking about.
They recorded numbers using the knots on a string called a quipu.
Subheadings give the reader an idea of what will be discussed in the section. For example, 'How Did WWII Shape Daily Life?' This subheading shows the reader that it will be about how WWII changed the daily lives of people. By the end of the section, the reader should have a firm answer to the question.
