When writing documents in TeX/LaTeX, it is important to understand how the TeX engine “thinks”. A paragraph is the basic text unit in a document and many TeX/LaTeX commands, when used properly, affect the current paragraph only. TeX provides a set of basic commands controlling the way a paragraphs are typeset. The following article explains the most commonly used commands and illustrates them with examples.
Any piece of text in TeX/LaTeX is a paragraph and follows predefined specifications. Single line-breaks will be ignored by the engine. To end a paragraph, leave a blank line between the end of the current and the beginning of the new paragraph.
...end of the current paragraph. Beginning of a new paragraph...
The second, indented line marks the beginning of a new paragraph.
Alternatively, \par
might be used to end a paragraph.
\documentclass{article} \usepackage{blindtext} \begin{document} \blindtext\par\blindtext \end{document}
Paragraph width
In plain TeX, \hsize
controls the paragraph width, set to 6.5in
by default. The example below shows how to change the paragraph width for a single paragraph.
\documentclass{article} \usepackage{blindtext} \begin{document} \blindtext \hsize 4in \blindtext \end{document}
The \leftskip
and \rightskip
commands provide a alternative, reducing the paragraph size from left and right respectively.
\documentclass{article} \usepackage{blindtext} \begin{document} \blindtext \leftskip=1.5in \blindtext \leftskip=0in \rightskip=1.5in \blindtext \end{document}
LaTeX knows at least two macros to control the paragraph width, the minipage
environment and the \parbox
command.
%Parbox macro \parbox{4in}{...} %Minipage environment \begin{minipage}{4in} ... \end{minipage}
Within a paragraph, the width is changed through the \hangindent
and \hangafter
commands. \hangindent
controls the amount of indentation from left (positive value) or right (negative value). \hangafter
, on the other hand, controls the number of full-width lines before changing the indent (\hangindent
). A positive number produces full-width lines at the beginning, whereas a negative number produces them at the end.
Here is an example reducing the paragraph width by 2in
from the right after the fifth line.
\documentclass[11pt]{article} \usepackage{blindtext} \begin{document} \hangindent=-2in \hangafter=5 \blindtext \blindtext \end{document}
Paragraph indentation
By default, TeX indents the first line of each paragraphs by 20pt
. The \parindent
command controls the indentation of paragraphs. To change the indentation document-wide, set \parindent
in the document preamble to the desired value. To disable the indentation for a single paragraph, use \noindent
at the beginning of the paragraph.
\documentclass{article} \usepackage{blindtext} \parindent=0pt % disables indentation \begin{document} \blindtext \blindtext \end{document}
Vertical space between paragraphs
TeX leaves no vertical space between paragraphs by default (\parskip=0pt
). Similar to \parindent
, setting \parskip
in the document preamble controls the vertical space between paragraphs document-wide.
\documentclass{article} \usepackage{blindtext} \parskip=12pt % adds vertical space between paragraphs \begin{document} \blindtext \blindtext \end{document}
Vertical space between lines
While using the default font size (10pt
), the line distance is 12pt
. A ratio of 1.2 (line height to font size) leaves enough space between lines for a good reading experience and gives a harmonious look. The line height can be changed through \baselineskip
.
More on font size in LaTeX.
\documentclass{article} \usepackage{blindtext} \begin{document} \blindtext \baselineskip=20pt \blindtext \end{document}
Further readings
A gentle introduction to TeX, a relatively short, but well written introduction to TeX by Michael Doob.