After having declared a class, in the preamble you can modify functionality in LaTeX by adding one or more packages. These can
The LaTeX ‘kernel’ (the core of LaTeX) is rather limited in user customisation,
and so some add-on packages deal with very common ideas. The first is to
change how LaTeX deals with language-specific typesetting (hyphenation,
punctuation, quotations, localisation, etc.). Different languages have different
rules, so it’s important to tell LaTeX which one to use. This is handled by the
babel package.
\documentclass{article}
\usepackage[T1]{fontenc}
%\usepackage[french]{babel}
\usepackage[width = 6cm]{geometry} % To force hyphenation here
\begin{document}
This is a lot of filler which is going to demonstrate how LaTeX hyphenates
material, and which will be able to give us at least one hyphenation point.
This is a lot of filler which is going to demonstrate how LaTeX hyphenates
material, and which will be able to give us at least one hyphenation point.
\end{document}
Try un-commenting the (clearly misleading) line to load babel and see the
effect. (The standard hyphenation rules are US English.)
The babel package does a lot more than hyphenation, depending on the language
involved; we’ve given some more details if you need them.
It’s useful to be able to adjust some aspects of design independent of the
document class. The most obvious one are the page margins. We’ve just used
the geometry package in the example above, but let’s now have an example
specifically about margins.
\documentclass{book}
\usepackage[T1]{fontenc}
\usepackage[margin=1in]{geometry}
\begin{document}
Hey world!
This is a first document.
% ================
\chapter{Chapter One}
Introduction to the first chapter.
\section{Title of the first section}
Text of material in the first section
Second paragraph.
\subsection{Subsection of the first section}
Text of material in the subsection.
% ================
\section{Second section}
Text of the second section.
\end{document}
You should see the effect here compared to not loading geometry.
One of LaTeX’s strengths is that you can choose from thousands of packages, including ones for writing mathematical text, for hyperlinking, for sophisticated capabilities with color, etc. We will see some more common packages in later lessons.
Sometimes you need a command specific to your document, either some functionality not found in the available packages or simply a command to enter a common expression that is used multiple times.
The following example shows a command to produce keywords with a specific style applied.
\documentclass{article}
\usepackage[T1]{fontenc}
\newcommand\kw[1]{\textbf{\itshape #1}}
\begin{document}
Something about \kw{apples} and \kw{oranges}.
\end{document}
In the definition #1 denotes the first argument that is supplied
(apples or oranges in this example). You may have up to nine
arguments, but it is usually best to have just one argument, or
sometimes none at all.
Defining commands does not just reduce the typing required to produce
a document. It helps to separate out the styling information. If it is
decided to use a different style for keywords, rather than having to
edit the entire document, you simply need to use a different
definition. Here we load the xcolor package to provide colors, and
use blue in place of bold in the formatting.
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{xcolor}
\newcommand\kw[1]{\textcolor{blue}{\itshape #1}}
\begin{document}
Something about \kw{apples} and \kw{oranges}.
\end{document}
Beware that defining too many commands or defining commands with multiple arguments may make the document source harder to understand as it is using an unfamiliar syntax. The ability to define document-specific commands should be used with care.
Try out writing some text in other European languages and see how babel
affects hyphenation: you can probably find some text on the internet, and guess
the right options.
Try altering the margins in the geometry example. You can set the individual
top, bottom, left and right margins separately using a comma-separated
list.
Try loading the lipsum package and then add the command \lipsum to your
document. Can you guess why this package is useful for making examples?
Try altering the definition of \kw to achieve a different style.