LaTeX Sections & Table of Contents: Complete Document Structure Guide

Document Hierarchy

LaTeX provides seven hierarchical levels for organizing document content. The available levels depend on your document class.

Complete Hierarchy

Document Class Differences

% article class (no chapters)
\documentclass{article}
\section{Introduction}
\subsection{Background}

% book/report class (with chapters)
\documentclass{book}
\chapter{Getting Started}
\section{Installation}
\subsection{Requirements}

% letter class (no sections)
\documentclass{letter}

Typical Usage Patterns

% Research paper (article)
\section{Introduction}
\section{Literature Review}
\subsection{Previous Work}
\section{Methodology}

% Book
\part{Foundations}
\chapter{Introduction}
\section{Overview}
\subsection{Key Concepts}

% Thesis (report)
\chapter{Introduction}
\section{Background}
\subsection{Related Work}

Basic Section Commands

Section commands create headings with automatic numbering, formatting, and table of contents entries.

Section Syntax

% Basic section
\section{Section Title}

% Optional short title for TOC
\section[Short Title]{Full Section Title}

% Unnumbered section
\section*{Unnumbered Section}

% Complete example
\section{Introduction}
This is the introduction content.

\subsection{Background}
Background information here.

\subsubsection{Historical Context}
Details about history.

Article Document Example

\documentclass{article}
\title{Research Paper Title}
\author{Author Name}
\date{\today}

\begin{document}

\maketitle

\section{Introduction}
Introduction text here.

\section{Methods}
\subsection{Data Collection}
How data was collected.

\subsection{Analysis}
How data was analyzed.

\section{Results}
\subsection{Findings}
What we found.

\section{Discussion}
Discussion of results.

\section{Conclusion}
Summary and conclusions.

\end{document}

All Section Levels

\section{Level 1: Section}
\subsection{Level 2: Subsection}
\subsubsection{Level 3: Subsubsection}
\paragraph{Level 4: Paragraph} Text continues immediately.
\subparagraph{Level 5: Subparagraph} Text continues.

Note: \paragraph and \subparagraph are run-in headings (text continues on same line).

Short Titles for TOC

% Long title in document, short in TOC
\section[Short]{Very Long Section Title That Would Clutter TOC}

% Useful for:
\section[Introduction]{Introduction to Advanced Topics in Machine Learning}

Automatic Numbering

LaTeX automatically numbers sections hierarchically. You can control numbering depth and format.

Unnumbered Sections

% Add asterisk for unnumbered sections
\section*{Abstract}
\section*{Acknowledgments}
\section*{References}

% Still numbered
\section{Introduction}

Controlling Numbering Depth

% Set which levels get numbered (default: 2 for article, 3 for book)
\setcounter{secnumdepth}{3}  % Number down to subsubsection

% Values:
% -1: part        (book only)
%  0: chapter     (book/report)
%  1: section
%  2: subsection
%  3: subsubsection
%  4: paragraph
%  5: subparagraph

% No numbering at all
\setcounter{secnumdepth}{-1}

Customizing Number Format

% Change section numbering style
\renewcommand{\thesection}{\Roman{section}}  % I, II, III
\renewcommand{\thesection}{\Alph{section}}   % A, B, C
\renewcommand{\thesection}{\arabic{section}} % 1, 2, 3 (default)

% Subsection format
\renewcommand{\thesubsection}{\thesection.\alph{subsection}}  % 1.a, 1.b

Manual Numbering

% Set section counter manually
\setcounter{section}{5}  % Next section will be 6

% Add to counter
\addtocounter{section}{2}  % Skip ahead by 2

% Reset subsection counter
\setcounter{subsection}{0}

Appendices

% Switch to appendix numbering
\appendix

\section{Supplementary Data}  % Becomes Appendix A
\section{Additional Proofs}  % Becomes Appendix B

% Or with explicit command
\begin{appendices}
  \section{First Appendix}
  \section{Second Appendix}
\end{appendices}

Table of Contents

LaTeX automatically generates a table of contents from section commands with the \tableofcontents command.

Basic Table of Contents

\documentclass{article}

\begin{document}

\tableofcontents  % Generates TOC
\newpage          % Start content on new page

\section{Introduction}
Content here.

\section{Methods}
More content.

\end{document}

Important: Compile twice—first run collects section info, second run generates TOC.

Controlling TOC Depth

% Set which levels appear in TOC (default: 2 for article, 3 for book)
\setcounter{tocdepth}{3}

% Values same as secnumdepth:
% -1: part
%  0: chapter
%  1: section
%  2: subsection
%  3: subsubsection

% Example: Only sections and subsections in TOC
\setcounter{tocdepth}{2}

Adding Unnumbered Sections to TOC

% Unnumbered section not in TOC
\section*{Abstract}

% Unnumbered but added to TOC
\section*{Acknowledgments}
\addcontentsline{toc}{section}{Acknowledgments}

% Simpler with package
\usepackage{tocbibind}  % Automatically adds bibliography, index

TOC Title Customization

% Change "Contents" title
\renewcommand{\contentsname}{Table of Contents}

% Or in different language
\renewcommand{\contentsname}{Innehåll}  % Swedish

Multiple TOCs

\usepackage{minitoc}

% Enable mini-TOCs per chapter
\dominitoc

\chapter{First Chapter}
\minitoc  % Chapter-specific TOC

Lists of Figures & Tables

Similar to table of contents, LaTeX can automatically generate lists of figures and tables.

List of Figures

% Generate list of figures
\listoffigures

% Changes appear with all \caption commands
\begin{figure}
  \includegraphics{image.png}
  \caption{This appears in list of figures}
  \label{fig:example}
\end{figure}

List of Tables

% Generate list of tables
\listoftables

% Captured from table captions
\begin{table}
  \begin{tabular}{cc}
    A & B \\
    C & D
  \end{tabular}
  \caption{This appears in list of tables}
  \label{tab:example}
\end{table}

Complete Front Matter Example

\documentclass{report}

\begin{document}

% Title page
\maketitle

% Front matter
\tableofcontents
\listoffigures
\listoftables

% Main content
\chapter{Introduction}
...

\end{document}

Short Captions for Lists

% Long caption in document, short in list
\caption[Short caption]{Very long detailed caption that would clutter the list of figures}

% Example
\caption[Neural network architecture]{Detailed neural network architecture showing all 12 layers with activation functions and dropout rates}

Customizing List Titles

% Change default titles
\renewcommand{\listfigurename}{List of Figures}
\renewcommand{\listtablename}{List of Tables}

Customization with titlesec

The titlesec package provides extensive control over section heading appearance.

Loading titlesec

\usepackage{titlesec}

Basic Formatting

% Change section format
\titleformat{\section}
  {\normalfont\Large\bfseries}  % Format
  {\thesection}                  % Label
  {1em}                          % Separation
  {}                             % Before-code

% Example: centered, large, bold sections
\titleformat{\section}
  {\centering\Large\bfseries}
  {\thesection}
  {1em}
  {}

Colored Section Headings

\usepackage{xcolor}
\usepackage{titlesec}

% Blue section headings
\titleformat{\section}
  {\color{blue}\normalfont\Large\bfseries}
  {\thesection}
  {1em}
  {}

% Different colors for different levels
\titleformat{\section}
  {\color{blue}\Large\bfseries}
  {\thesection}{1em}{}
\titleformat{\subsection}
  {\color{cyan}\large\bfseries}
  {\thesubsection}{1em}{}

Custom Section Styles

% Underlined sections
\titleformat{\section}
  {\normalfont\Large\bfseries}
  {\thesection}
  {1em}
  {}
  [\titlerule]  % Horizontal line after

% Boxed sections
\titleformat{\section}
  {\normalfont\Large\bfseries}
  {\thesection}
  {1em}
  {\fbox}

Spacing Control

% Adjust spacing before and after sections
\titlespacing{\section}
  {0pt}      % Left margin
  {12pt}     % Space before
  {6pt}      % Space after

% Compact sections (resume-style)
\titlespacing{\section}
  {0pt}{8pt}{4pt}
\titlespacing{\subsection}
  {0pt}{6pt}{3pt}

Resume Section Formatting

\usepackage{titlesec}
\usepackage{xcolor}

% Define color
\definecolor{primary}{HTML}{2C3E50}

% Custom section format for resume
\titleformat{\section}
  {\color{primary}\Large\bfseries}
  {}
  {0em}
  {}
  [\color{primary}\titlerule]

% Reduce spacing
\titlespacing{\section}
  {0pt}{10pt}{5pt}

Sections for Resumes

Resume sections require different formatting than academic documents—minimal spacing, clear hierarchy, professional appearance.

Basic Resume Structure

\documentclass{article}
\usepackage[margin=0.75in]{geometry}
\pagestyle{empty}

\begin{document}

% Header (name and contact)
{\Huge\bfseries John Doe}

\section*{Experience}
\textbf{Senior Developer} | Company Name \hfill 2020--Present

\section*{Education}
\textbf{BS Computer Science} | University Name \hfill 2016--2020

\section*{Skills}
Python, JavaScript, React, Node.js

\end{document}

Custom Resume Section Command

\usepackage{xcolor}

% Define color
\definecolor{primary}{HTML}{2C3E50}

% Custom section command
\newcommand{\cvsection}[1]{%
  \vspace{10pt}
  {\color{primary}\Large\bfseries #1}
  \vspace{2pt}
  {\color{primary}\hrule height 1pt}
  \vspace{5pt}
}

% Usage
\cvsection{Professional Experience}
\cvsection{Education}
\cvsection{Technical Skills}

Two-Column Resume Sections

\usepackage{paracol}

\begin{paracol}{2}

% Left column (narrow)
\section*{Skills}
Python \\
JavaScript \\
SQL

\switchcolumn

% Right column (wide)
\section*{Experience}
\textbf{Developer} \\
Company Name

\end{paracol}

Minimal Spacing Resume

\documentclass[10pt]{article}
\usepackage[margin=0.5in]{geometry}
\usepackage{titlesec}

% Remove section numbering
\setcounter{secnumdepth}{0}

% Compact section formatting
\titleformat{\section}
  {\large\bfseries}
  {}
  {0em}
  {}
  [\vspace{-10pt}\hrule\vspace{2pt}]

\titlespacing{\section}
  {0pt}{8pt}{3pt}

% Remove paragraph indentation
\setlength{\parindent}{0pt}

Skills Section with Categories

\section*{Technical Skills}

\textbf{Languages:} Python, JavaScript, Java, C++ \\
\textbf{Frameworks:} React, Django, Spring Boot \\
\textbf{Databases:} PostgreSQL, MongoDB, Redis \\
\textbf{Tools:} Git, Docker, Kubernetes, AWS

Hyperlinks & Navigation

The hyperref package adds clickable links to table of contents, references, and URLs.

Loading hyperref

% Load hyperref (should be loaded last)
\usepackage{hyperref}

% With color options
\usepackage[
  colorlinks=true,
  linkcolor=blue,
  urlcolor=blue,
  citecolor=blue
]{hyperref}

Clickable Table of Contents

\usepackage{hyperref}

% TOC entries become clickable links
\tableofcontents

% Clicking on "2.1 Background" jumps to that section

Internal Links

% Label a section
\section{Introduction}
\label{sec:intro}

% Link to it
See Section~\ref{sec:intro} for details.

% Or with hyperref
See Section~\hyperref[sec:intro]{Introduction}.

External Links (URLs)

% Clickable URLs
\href{https://example.com}{Click here}

% Display URL
\url{https://example.com}

% Email
\href{mailto:john@example.com}{john@example.com}

% Resume contact info with links
Email: \href{mailto:john@example.com}{john@example.com} \\
Portfolio: \href{https://johndoe.com}{johndoe.com} \\
LinkedIn: \href{https://linkedin.com/in/johndoe}{linkedin.com/in/johndoe}

Customizing Link Appearance

% Colored links (recommended)
\hypersetup{
  colorlinks=true,
  linkcolor=blue,
  urlcolor=blue,
  citecolor=blue
}

% Boxed links (default, often distracting)
\hypersetup{
  colorlinks=false,
  linkbordercolor=red
}

% No visual distinction (not recommended)
\hypersetup{
  hidelinks
}

PDF Metadata

\hypersetup{
  pdftitle={My Document Title},
  pdfauthor={Author Name},
  pdfsubject={Subject},
  pdfkeywords={keyword1, keyword2}
}

Advanced Techniques

Mini Table of Contents

\usepackage{minitoc}

\dominitoc  % Enable mini-TOCs
\tableofcontents

\chapter{First Chapter}
\minitoc  % Local TOC for this chapter
\section{Section One}
\section{Section Two}

Custom List of Items

% Create custom list (like LOF/LOT)
\usepackage{tocloft}

% Define new list
\newlistof{algorithm}{loa}{List of Algorithms}

% Add entries
\refstepcounter{algorithm}
\addcontentsline{loa}{algorithm}{Algorithm Name}

% Generate list
\listofalgorithms

Conditional Sections

% Include sections conditionally
\newif\ifdetailed
\detailedtrue  % or \detailedfalse

\ifdetailed
  \section{Detailed Analysis}
  Content for detailed version.
\fi

Section Breaks

% Decorative section break
\newcommand{\sectionbreak}{%
  \vspace{10pt}
  \noindent\makebox[\linewidth]{\rule{0.5\paperwidth}{0.4pt}}
  \vspace{10pt}
}

\section{First Section}
Content.
\sectionbreak
\section{Second Section}

Numbered Paragraphs

% Make paragraph numbered like section
\setcounter{secnumdepth}{4}

\paragraph{First Point}
This paragraph is numbered.

\paragraph{Second Point}
This one too.

Running Headers with Sections

\usepackage{fancyhdr}

\pagestyle{fancy}
\fancyhead[L]{\leftmark}  % Chapter/section name
\fancyhead[R]{\thepage}

% Left mark shows chapter, right mark shows section
\fancyhead[L]{\rightmark}

Troubleshooting

TOC Not Updating

Problem: Changes to sections don't appear in table of contents.

Solution: Compile twice (or delete .aux files):

% First compile: collects section information
% Second compile: generates TOC with collected info

% Or delete auxiliary files
rm document.aux document.toc

Chapter Not Defined

Problem: ! Undefined control sequence. \chapter

Solution: Chapters only exist in book/report classes:

% Wrong (article doesn't have chapters)
\documentclass{article}
\chapter{Introduction}  % Error!

% Correct
\documentclass{book}
\chapter{Introduction}  % OK

% Or use section in article
\documentclass{article}
\section{Introduction}  % OK

Section Numbers Wrong

Problem: Numbering restarts or skips numbers.

Solution: Check for manual counter changes:

% If you manually set counters, numbering can be affected
\setcounter{section}{0}  % Resets to 0

% Use \refstepcounter for proper references
\refstepcounter{section}

TOC Too Deep or Too Shallow

Problem: TOC shows too many or too few levels.

Solution: Adjust tocdepth:

% Show more levels
\setcounter{tocdepth}{3}  % Include subsubsections

% Show fewer levels
\setcounter{tocdepth}{1}  % Only sections

Sections Have No Numbers

Problem: All sections appear without numbers.

Solutions:

% Check if secnumdepth is too low
\setcounter{secnumdepth}{3}  % Number down to subsubsection

% Check if using starred versions
\section{Title}   % Numbered
\section*{Title}  % Unnumbered

Hyperref Conflicts

Problem: Errors when loading hyperref with other packages.

Solution: Load hyperref last:

% Load other packages first
\usepackage{graphicx}
\usepackage{amsmath}
\usepackage{titlesec}

% Load hyperref last
\usepackage{hyperref}

Frequently Asked Questions

\documentclass{article}

\begin{document}

\section{Introduction}
Introduction text here.

\subsection{Background}
Background information.

\section{Methods}
Methods description.

\end{document}

\documentclass{article}

\begin{document}

\tableofcontents  % Generates TOC
\newpage

\section{Introduction}
\section{Methods}
\section{Results}

\end{document}

% Unnumbered section
\section*{Abstract}
\section*{Acknowledgments}

% Regular numbered section
\section{Introduction}

\section*{Abstract}
\addcontentsline{toc}{section}{Abstract}

\section{Main Topic}
  \subsection{Subtopic}
    \subsubsection{Detailed Point}

% Roman numerals (I, II, III)
\renewcommand{\thesection}{\Roman{section}}

% Letters (A, B, C)
\renewcommand{\thesection}{\Alph{section}}

% Standard numbers (default)
\renewcommand{\thesection}{\arabic{section}}

% Custom format
\renewcommand{\thesection}{Chapter \arabic{section}}

% Show only sections (depth 1)
\setcounter{tocdepth}{1}

% Show sections and subsections (depth 2, default)
\setcounter{tocdepth}{2}

% Show down to subsubsections (depth 3)
\setcounter{tocdepth}{3}

% Values:
% -1: part
%  0: chapter
%  1: section
%  2: subsection
%  3: subsubsection

\usepackage{titlesec}
\usepackage{xcolor}

% Custom section format
\titleformat{\section}
  {\color{blue}\Large\bfseries}  % Format
  {\thesection}                   % Label
  {1em}                           % Separation
  {}                              % Before-code
  [\titlerule]                    % After-code (underline)

% Adjust spacing
\titlespacing{\section}
  {0pt}   % Left
  {12pt}  % Before
  {6pt}   % After

\documentclass{article}

\begin{document}

\tableofcontents
\listoffigures
\listoftables

\section{Results}

\begin{figure}
  \caption{My figure}  % Appears in list of figures
\end{figure}

\begin{table}
  \caption{My table}  % Appears in list of tables
\end{table}

\end{document}

\usepackage[colorlinks=true,linkcolor=blue]{hyperref}

% TOC entries become clickable automatically
\tableofcontents

% Create links manually
\section{Introduction}
\label{sec:intro}

% Link to it
See Section~\ref{sec:intro}.

% External URLs
\href{https://example.com}{Click here}
\url{https://example.com}

% Unnumbered sections (recommended for resumes)
\section*{Experience}
\section*{Education}
\section*{Skills}

% Or disable numbering globally
\setcounter{secnumdepth}{0}

\section{Experience}  % Won't be numbered
\section{Education}