Getting Started

Understanding the LaTeX Preamble and Document Structure

Every LaTeX document has two parts: the preamble (settings/packages) and the document body (content). Understanding this structure is key to customizing your documents.

Document Structure

The two main parts:

% ===== PREAMBLE (before \begin{document}) =====
\documentclass[12pt]{article}  % Document type
\usepackage{graphicx}          % Packages
\title{My Paper}               % Metadata
\author{John Smith}

% ===== BODY (between begin/end document) =====
\begin{document}
\maketitle
Your content goes here...
\end{document}

Document Class

First line - sets document type:

% Basic classes:
\documentclass{article}  % Short documents
\documentclass{report}   % Chapters, longer works
\documentclass{book}     % Two-sided, chapters
\documentclass{letter}   % Letters

% With options:
\documentclass[12pt,a4paper,twocolumn]{article}

% Journal classes:
\documentclass{IEEEtran}
\documentclass{elsarticle}

Loading Packages

Add features with \usepackage:

% Essential packages:
\usepackage{graphicx}    % Images
\usepackage{amsmath}     % Math features
\usepackage{hyperref}    % Clickable links
\usepackage{geometry}    % Page layout
\usepackage{biblatex}    % Modern citations

% Package with options:
\usepackage[margin=1in]{geometry}
\usepackage[colorlinks=true]{hyperref}

Custom Commands

Define shortcuts in preamble:

% Custom commands save typing:
\newcommand{\R}{\mathbb{R}}  % \R → ℝ
\newcommand{\vect}[1]{\mathbf{#1}}  % \vect{x} → x (bold)

% Then in document:
Let $x \in \R$ and $\vect{v}$ be a vector.

💡 Tips

•Keep preamble organized: class, packages, custom commands, metadata
•Package order can matter - load hyperref last usually
•For large projects, put preamble in a separate .tex file and \input it

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