Packages are libraries that extend LaTeX's capabilities. You load them in the preamble.

Level 1: Essential Packages

LaTeX

\usepackage{amsmath} % Advanced math
\usepackage{graphicx} % Images
\usepackage{hyperref} % Clickable links

Level 2: Package Options

Many packages accept arguments in square brackets.

LaTeX

\usepackage[margin=1in]{geometry} % Set margins
\usepackage[utf8]{inputenc} % Encoding
\usepackage[style=apa]{biblatex} % Reference style

Level 3: Custom Commands

Create your own shortcuts for repetitive tasks.

Source Code

Example OutputStatic

% In preamble: \newcommand{\R}{\mathbb{R}} \newcommand{\alert}[1]{\textbf{\textcolor{red}{#1}}} % In document: The set of real numbers is $\R$. \alert{Do not forget this!}

The set of real numbers is ℝ.

Do not forget this!