By default, LaTeX uses quite wide margins to optimize readability (the "golden line length"). However, for assignments, lab reports, and theses, you will often need to customize your page layout. The easiest and most powerful way to do this is using the geometry package.
To modify your margins and orientation, you must load the package in your preamble (the section of code before \begin{document}).
\usepackage[options]{geometry}
Margin Configurations
Standard Margin Configuration
If you want to set uniform margins across your entire document (e.g., 1 inch or 2.5 cm on all sides), use the following code:
\documentclass{article}
% Loading the geometry package with specific margins
\usepackage[margin=1in]{geometry}
\begin{document}
Your text goes here. The margins on all four sides are now exactly 1 inch.
\end{document}
Customizing Individual Sides
If your document features a wide table or a large chart, you can change the orientation of the entire document to landscape.
\usepackage[top=2cm, bottom=2cm, left=3cm, right=2cm]{geometry}