Time for action – adding a table of contents

We shall create a table of contents based on our numbered headings.

1. Let's remove the options landscape and twocolumn. We also don't load the setspace package. Add the command \tableofcontents right after \begin{document}. Our code shall now be:

   \documentclass[a4paper,12pt]{book}
   \usepackage[english]{babel}
   \usepackage{blindtext}
   \usepackage[a4paper, inner=1.5cm, outer=3cm, top=2cm,
   bottom=3cm, bindingoffset=1cm]{geometry}
   \begin{document}
   \tableofcontents
   \chapter{Exploring the page layout}
   In this chapter we will study the layout of pages.
   \section{Some filler text}
   \blindtext
   \section{A lot more filler text}
   More dummy text will follow.
   \subsection{Plenty of filler text}
   \blindtext[10]
   \end{document}

2. Typeset twice. Afterwards, the first page of your output will contain this table:

   

What just happened?

The command \tableofcontents tells LaTeX to produce a file with the extension .toc. This file will be used to generate a table of contents. We had to...