> ## Documentation Index
> Fetch the complete documentation index at: https://resources.latex-cloud-studio.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Document Structure

> Understanding LaTeX document structure, classes, and organization

Every LaTeX document follows a specific structure that separates content from formatting. Understanding this structure is essential for creating well-organized documents.

## Basic Document Structure

A LaTeX document consists of two main parts:

```latex theme={null}
\documentclass{article}  % Preamble starts here

% Package imports
\usepackage{graphicx}
\usepackage{amsmath}

% Document settings
\title{My Document}
\author{Your Name}

\begin{document}        % Document body starts here

\maketitle

Your content goes here...

\end{document}
```

<Info>
  The **preamble** (before `\begin{document}`) contains global settings, package imports, and definitions. The **document body** (between `\begin{document}` and `\end{document}`) contains your actual content.
</Info>

## Document Classes

The document class determines the overall layout and available commands:

### Standard Classes

```latex theme={null}
\documentclass[options]{class}
```

| Class     | Purpose                   | Key Features                                    |
| --------- | ------------------------- | ----------------------------------------------- |
| `article` | Short documents, papers   | No chapters, sections start at 1                |
| `report`  | Technical reports, theses | Chapters available, new chapter starts new page |
| `book`    | Books, long documents     | Two-sided by default, chapters, parts           |
| `letter`  | Correspondence            | Special letter commands                         |
| `beamer`  | Presentations             | Slides, overlays, themes                        |

### Class Options

Common options for document classes:

```latex theme={null}
\documentclass[11pt,a4paper,twocolumn]{article}
```

<CodeGroup>
  ```latex Font Size theme={null}
  % Available sizes
  \documentclass[10pt]{article}   % Default
  \documentclass[11pt]{article}
  \documentclass[12pt]{article}
  ```

  ```latex Paper Size theme={null}
  % Common paper sizes
  \documentclass[a4paper]{article}     % A4 (210 × 297 mm)
  \documentclass[letterpaper]{article} % US Letter (8.5 × 11 in)
  \documentclass[a5paper]{article}     % A5 (148 × 210 mm)
  \documentclass[legalpaper]{article}  % US Legal (8.5 × 14 in)
  ```

  ```latex Layout Options theme={null}
  % Single/double sided
  \documentclass[oneside]{report}  % Single-sided
  \documentclass[twoside]{report}  % Double-sided (default for book)

  % Column layout
  \documentclass[onecolumn]{article}  % Default
  \documentclass[twocolumn]{article}  % Two columns

  % Orientation
  \documentclass[landscape]{article}  % Landscape mode
  ```
</CodeGroup>

## Document Organization

### Title Information

```latex theme={null}
% In preamble
\title{Document Title}
\author{First Author \and Second Author}
\date{\today}  % or \date{January 2024}

% In document
\begin{document}
\maketitle  % Creates title block
```

### Abstract

For articles and reports:

```latex theme={null}
\begin{abstract}
This is a brief summary of the document's contents,
typically 150-250 words.
\end{abstract}
```

### Sectioning Commands

LaTeX provides hierarchical sectioning:

```latex theme={null}
% Book/Report class
\part{Part Title}
\chapter{Chapter Title}
\section{Section Title}
\subsection{Subsection Title}
\subsubsection{Subsubsection Title}
\paragraph{Paragraph Title}
\subparagraph{Subparagraph Title}

% Article class (no \chapter)
\part{Part Title}
\section{Section Title}
\subsection{Subsection Title}
% ... continues same as above
```

<Tip>
  Use starred versions for unnumbered sections: `\section*{Introduction}`
</Tip>

### Table of Contents

```latex theme={null}
\tableofcontents  % Generates TOC
\listoffigures    % List of figures
\listoftables     % List of tables

% Control TOC depth
\setcounter{tocdepth}{2}  % Show up to subsections
```

## Page Layout

### Margins and Geometry

Using the `geometry` package:

```latex theme={null}
\usepackage{geometry}
\geometry{
    a4paper,
    left=2.5cm,
    right=2.5cm,
    top=3cm,
    bottom=3cm
}
```

### Headers and Footers

Basic page numbering:

```latex theme={null}
\pagestyle{plain}    % Page number at bottom center
\pagestyle{empty}    % No headers or footers
\pagestyle{headings} % Chapter/section in header
```

Custom headers with `fancyhdr`:

```latex theme={null}
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{}  % Clear all
\fancyhead[L]{Left Header}
\fancyhead[C]{Center Header}
\fancyhead[R]{Right Header}
\fancyfoot[C]{\thepage}
```

## Multi-file Documents

For large documents, split content into multiple files:

### Main File (thesis.tex)

```latex theme={null}
\documentclass{report}
\usepackage{...}

\begin{document}

\include{chapters/introduction}
\include{chapters/methodology}
\include{chapters/results}
\include{chapters/conclusion}

\bibliographystyle{plain}
\bibliography{references}

\end{document}
```

### Chapter File (chapters/introduction.tex)

```latex theme={null}
\chapter{Introduction}

This chapter introduces...

\section{Background}
Content...
```

<Info>
  **`\include` vs `\input`:**

  * `\include{file}` - Starts new page, allows `\includeonly`
  * `\input{file}` - Inserts content inline, no page break
</Info>

## Appendices

```latex theme={null}
\appendix  % Switch to appendix mode

\chapter{Additional Data}  % Becomes "Appendix A"
Content...

\chapter{Source Code}      % Becomes "Appendix B"
Content...
```

## Front Matter and Back Matter

For books and reports:

```latex theme={null}
\begin{document}

\frontmatter  % Roman numerals, no chapter numbers
\maketitle
\tableofcontents
\listoffigures

\mainmatter   % Arabic numerals, normal numbering
\chapter{Introduction}
% Main content...

\backmatter   % No chapter numbers
\bibliography{refs}
\printindex

\end{document}
```

## Best Practices

<Tip>
  **Document structure tips:**

  1. **Use consistent sectioning** - Don't skip levels
  2. **Organize with files** - One chapter per file for large documents
  3. **Comment your preamble** - Document package purposes
  4. **Use logical labels** - `\label{sec:intro}` not `\label{s1}`
  5. **Keep preamble clean** - Move custom commands to separate file
</Tip>

## Common Patterns

### Academic Article

```latex theme={null}
\documentclass[12pt,a4paper]{article}
\usepackage{amsmath,graphicx,hyperref}

\title{Research Title}
\author{Author Name\\Institution}
\date{\today}

\begin{document}
\maketitle
\begin{abstract}
Summary...
\end{abstract}

\section{Introduction}
\section{Methodology}
\section{Results}
\section{Conclusion}

\bibliographystyle{plain}
\bibliography{references}
\end{document}
```

### Technical Report

```latex theme={null}
\documentclass[11pt,a4paper]{report}
\usepackage{geometry,fancyhdr,graphicx}

\begin{document}
\frontmatter
\maketitle
\tableofcontents

\mainmatter
\chapter{Executive Summary}
\chapter{Technical Details}
\chapter{Implementation}

\appendix
\chapter{Additional Information}

\backmatter
\bibliography{refs}
\end{document}
```

***

Next: Explore [Text Formatting](/components/text-formatting) commands or learn about [Math Mode](/components/math-mode) for mathematical content.