\chapter{Basic document structure}
\label{sec:basic-document-structure}

In essence, every \LaTeX{} document is composed of two parts: 
We call the first commands within our \LaTeX{} document the \emph{preamble}.
It \replaced[id=F]{specifies global properties of}{contains global information about} our document, such as the document class, the encoding, the language, the page format, and additional packages that we want to use.
The \emph{document environment}, on the other hand, contains the actual content of our document, i.\,e., the things that we will later see in our generated \acro{PDF} file. 

\Example{lst:latex-document-basic-structure}{basic-document-structure/hello-world}{basic-document-structure/hello-world_crop}{Exemplary structure of a simple \LaTeX{} document with preamble and document environment}

\section{Preamble}
Let's take a closer look at the preamble. 
A minimal preamble should contain the following specifications: 

\subsection{Document class}\label{sec:document-class}
We can define a document class by using the command \mintinline[breaklines,breakafter=\]]{latex}|\documentclass[<parameter>]{<document class>}|. 
\todo{Was verursacht diese komische Klammer nach dem Befehl?}
The most commonly used document classes that are supported by default are \mintinline{latex}{article} for short documents, and \mintinline{latex}{report} for longer ones. 
Furthermore, you can use \mintinline{latex}{book} for books, \mintinline{latex}{beamer}\footnote{We do not cover making presentations in \LaTeX{} in this tutorial. However, if you are interested in the topic, we recommend this introduction on Overleaf: \url{https://www.overleaf.com/learn/latex/Beamer}} for presentations, and \mintinline{latex}{letter}\footnote{We also do not cover letters in this script. An introduction can be found on WikiBooks: \url{https://en.wikibooks.org/wiki/LaTeX/Letters}} for letters.

In addition to the standard document classes, the \acro{KOMA} script classes have been developed. 
They provide alternatives to the document classes mentioned above: 
In lieu of \mintinline{latex}{article} you can use \mintinline{latex}{scrartcl}, \mintinline{latex}{report} is replaced by \mintinline{latex}{scrreport}, and \mintinline{latex}{scrbook} can be used instead of \mintinline{latex}{book}. 
As a replacement for \mintinline{latex}{letter}, one can use \mintinline{latex}{scrlttr2}. 
A complete list of all \acro{KOMA} script classes is available online.\footnote{Available at: \url{https://komascript.de/omascriptbestandteile}} 
By using \acro{KOMA} document classes, the layout of the generated \acro{PDF} document is changed. 
On top of that, they provide additional functionalities. 
The standard document classes are designed according to the American-English 
standards whereas \acro{KOMA} classes adhere to European norms, e.\,g., for 
writing letters. 

Each \mintinline{latex}{\documentclass} command can hold optional parameters in 
square brackets. 
\mintinline{latex}{\documentclass[10pt,a5paper,landscape]{scrartcl}}, for instance, configures a \acro{KOMA} script article and sets its font size to 10\,pt,\footnote{The standard font size is 12\,pt.} the page size to A5,\footnote{The default case would be A4.} and the orientation of the page to landscape. 
The language can be passed as an optional parameter, too (cf. \cref{sec:language}). 

\subsection{Digression: packages}
\label{sec:packages}
\todo{Muss ``packages'' hier jetzt groß oder klein?}

\begin{minted}{latex}
\usepackage[<options>]{<packagename>}
\end{minted}

Packages provide additional commands and functionalities that we can use within our \LaTeX{} source code. 
There are numerous packages for different use cases (e.\,g., typesetting formulas, lists, \textellipsis). 
In order to use a package, it must be included within the preamble. 
To do so, the above-mentioned command is used. 
The most important \LaTeX{} packages can be found in the Comprehensive \TeX\ Archive Network,\footnote{Available at: \url{https://www.ctan.org/}} short: \acro{CTAN}. 
You can also find the documentation for the packages there. 

\subsection{Encoding}
\begin{minted}{latex}
\usepackage[utf8]{inputenc}
\usepackage[t1]
\end{minted}

One use case for packages is specifying the encoding of our \LaTeX{} document. 
The character encoding\footnote{cf. \url{https://en.wikipedia.org/wiki/Character_encoding}} determines the available character set.
The standard encoding in \LaTeX{} is \acro{ASCII}.\footnote{cf. \url{https://en.wikipedia.org/wiki/ASCII}}
It is an American character encoding and therefore does, for instance, not contain German umlauts, or other special characters, which makes it unsuitable for most use cases. 
As a consequence, \acro{UTF-8}\footnote{cf. \url{https://en.wikipedia.org/wiki/UTF-8}} can be used as a universal character encoding.

In \LaTeX{}, we need to specify two character encodings: 
The input encoding (short: \mintinline{latex}{inputenc}), which refers to our source code, and the font encoding (short: \mintinline{latex}{fontenc}), which concerns the choice of the file that is used to portray the content within our \acro{PDF} document, since we also need special characters there.
\todo{fontenc wird hier sehr umständlich beschrieben bzw. ist in dieser Detailtiefe nicht unbedingt relevant}
\todo{Wie wäre es mit \enquote{\[...\] and the font encoding, which determines how the content of our PDF document looks like.} oder so ähnlich?}
\footnote{Details on \mintinline{latex}{fontenc} can be found at: \url{https://tex.stackexchange.com/questions/108417/font-encoding-in-latex}}
\mintinline{latex}{T1} is an encoding that tries to cover most European languages with a limited number of characters. 

\subsection{Language}\label{sec:language}
\begin{minted}{latex}
\usepackage[ngerman]{babel}
\end{minted}

The package \mintinline{latex}{babel} provides language-specific information (e.\,g., on hyphenation, special characters, changing fonts, translation of labels\footnote{cf. \cref{sec:references}} like \enquote{Chapter}, \enquote{Table of Contents}, or \enquote{Figure}, \textellipsis).
The desired language can be passed as an optional parameter. 
\mintinline{latex}{ngerman}, for instance, is used for the new German spelling. 
Some packages require that the language is already passed as an optional parameter in the \mintinline{latex}{\documentclass} command. 
In this case, just leave out the optional parameter for the language within the \mintinline{latex}{babel} \added[id=F]{inclusion} command.

We can also use multiple languages in our document. 
To do so, we pass the languages, separated by commas, as an optional parameter to the \replaced[id=F]{babel inclusion}{\mintinline{latex}{\babel}} command. 
Within our document, we can switch between languages with the \mintinline{latex}{\selectlanguage{<language>}} command. 
Alternatively, foreign-language text can be declared by using the following command: 

\begin{minted}{latex}
\foreignlanguage{<language>}{<text>}
\end{minted}

\section{Document environment}
The actual content of the \acro{PDF} document needs to be put between \mintinline{latex}{\begin{document}} and \mintinline{latex}{\end{document}}.

\subsection{Continuous text}
The easiest content that we can integrate into the document environment is continuous text. 
We can write it directly into our source code. 
Line breaks and multiple \added[id=F]{consecutive} spaces are ignored by \LaTeX{}. 
Blank lines create a new paragraph, that is indented by default.
\footnote{The automatic indentation of new paragraphs can be prevented by using the command \mintinline{latex}{\noindent}.}
Manual line breaks can be enforced with two backslashes (\textbackslash\textbackslash). 
This should be avoided, though. 

\subsection{Comments}
Some characters are reserved for \LaTeX-specific commands, for instance, the percent sign. 
Using a percent sign tells the \LaTeX{} compiler to ignore the rest of the line, i.\,e., the text after the percent character will not appear in the generated \acro{PDF} document.
This can be useful in order to take notes while working on a document without affecting the document itself. 
\replaced[id=F]{It}{This} is called a comment.

However, if we want the percent sign to actually appear in the text, we can achieve this by using a backslash: \mintinline{latex}{\%}.
This solution is called escaping and also works for other reserved characters, like \#, \$, \&, \_, \{ and \}.

In order to escape the backslash, the command \mintinline{latex}{\textbackslash} must be used.
\footnote{An overview of additional special characters can be found in \cref{sec:special-characters}.}

\subsection{Sections and chapters}
Continuous text can be structured by headings that divide the document into sections and chapters. 
Needless to say, \LaTeX{} provides us with commands for that.
The commands that are depicted in \cref{lst:headlines} can be used with any document class. 

\Example{lst:headlines}{basic-document-structure/headlines}{basic-document-structure/headlines_crop}{Heading Levels}
\todo{Beispiele neu generieren.}

Depending on your specified document class, the commands \mintinline{latex}{\chapter{Chapter}} and \mintinline{latex}{\part{Part}} are additionally available -- for instance in books. 
You can mark the command with an asterisk if you want to omit the numbering of a section and exclude it from the table of contents:\footnote{cf. \cref{sec:table-of-contents}}

\begin{minted}{latex}
\section*{This section is excluded from the table of contents}
\end{minted}

An alternative title for the table of contents can be declared as an optional parameter in square brackets between the command and the actual title:

\begin{minted}{latex}
\section[Title in the TOC]{Actual Chapter Title}
\end{minted}

\subsection{Front matter}
A simple front matter can be created by using the command \mintinline{latex}{\maketitle}. 
The values \replaced[id=F]{to be}{that get} inserted into the front matter must be specified within the preamble. 
Multiple authors are joined by \mintinline{latex}{\and}.
If the date is not specified by the \mintinline{latex}{\date} command, the current date will be inserted by default.
The design of the front matter depends on the specified document class.

\Example{lst:titles}{basic-document-structure/titles}{basic-document-structure/titles_crop}{The front matter}

\subsection{Indices}\label{sec:table-of-contents}

The command \mintinline{latex}{\tableofcontents} generates an automatically numbered table of contents by making use of the above-mentioned commands for dividing our text into sections and chapters (this can bee seen in \cref{lst:main-file} on \cpageref{lst:main-file}).

The numbering style and depth, and many other options can, of course, be specified manually.
\footnote{We recommend the following blogpost: \url{https://texblog.org/2011/09/09/10-ways-to-customize-tocloflot/}}
For \LaTeX{} to create our table of contents properly, the project has to be compiled twice.

Besides the table of contents, you can also generate a \mintinline{latex}{\listoffigures} (list of figures) and a \mintinline{latex}{\listoftables} (list of tables). 
The captions of your figures and tables will appear within those indices.
\footnote{cf. \cref{sec:graphics} (Graphics) and \cref{sec:tables} (Tables) for more information on captions}
