Making paragraphs (LaTeX2e unofficial reference manual (October 2018))

## Making paragraphs

To start a paragraph, just type some text. To end the current paragraph, put an empty line. This is three paragraphs, separated by two empty lines.

    It is a truth universally acknowledged, that a single man in possession
    of a good fortune, must be in want of a wife.

    However little known the feelings or views of such a man may be on his
    first entering a neighbourhood, this truth is so well fixed in the minds
    of the surrounding families, that he is considered the rightful property
    of some one or other of their daughters.

    ``My dear Mr. Bennet,'' said his lady to him one day,
    ``have you heard that Netherfield Park is let at last?''

The separator lines must be empty, including not containing a comment character, `%`.

Once LaTeX has gathered all of a paragraph’s contents it divides that content into lines in a way that is optimized over the entire paragraph (see Line breaking).

There are places where a new paragraph is not permitted. Don’t put a blank line in math mode (see Modes); here the line before the `\end{equation}`

    \begin{equation}
      2^{|S|} > |S|

    \end{equation}

will get you the error ‘`Missing $ inserted`’. Similarly, the blank line in this `section` argument

    \section{aaa

    bbb}

gets ‘`Runaway argument? {aaa ! Paragraph ended before \@sect was complete`’.

### `\par`

Synopsis (note that while reading the input TeX converts two consecutive newlines to a `\par`):

    \par

End the current paragraph. The usual way to separate paragraphs is with a blank line but the `\par` command is entirely equivalent. This command is robust (see \protect).

This example uses `\par` rather than a blank line simply for readability.

    \newcommand{\syllabusLegalese}{%
      \whatCheatingIs\par\whatHappensWhenICatchYou}

In LR mode or a vertical mode the `\par` command does nothing but it terminates paragraph mode, switching LaTeX to vertical mode (see Modes).

You cannot use the `\par` command in a math mode. You also cannot use it in the argument of many commands, such as the `\section` command (see Making paragraphs and \newcommand & \renewcommand).

The `\par` command is not the same as the `\paragraph` command. The latter is, like `\section` or `\subsection`, a sectioning unit used by the standard LaTeX documents (see \subsubsection & \paragraph & \subparagraph).

The `\par` command is not the same as `\newline` or the line break double backslash, `\\`. The difference is that `\par` ends the paragraph, not just the line, and also triggers the addition of the between-paragraph vertical space `\parskip` (see \parindent & \parskip).

The output from this example

    xyz

    \setlength{\parindent}{3in}
    \setlength{\parskip}{5in}
    \noindent test\indent test1\par test2

is: after ‘`xyz`’ there is a vertical skip of 5 inches and then ‘`test`’ appears, aligned with the left margin. On the same line, there is an empty horizontal space of 3 inches and then ‘`test1`’ appears. Finally. there is a vertical space of 5 inches, followed by a fresh paragraph with a paragraph indent of 3 inches, and then LaTeX puts the text ‘`test2`’.

### `\indent` & `\noindent`

Synopsis:

    \indent

or

    \noindent

Go into horizontal mode (see Modes). The `\indent` command first outputs an empty box whose width is `\parindent`. These commands are robust (see \protect).

Ordinarily you create a new paragraph by putting in a blank line. See \par for the difference between this command and `\par`. To start a paragraph without an indent, or to continue an interrupted paragraph, use `\noindent`.

In the middle of a paragraph the `\noindent` command has no effect, because LaTeX is already in horizontal mode there. The `\indent` command’s only effect is to output a space.

This example starts a fresh paragraph.

    ... end of the prior paragraph.

    \noindent This paragraph is not indented.

and this continues an interrupted paragraph.

    The data

    \begin{center}
      \begin{tabular}{rl} ... \end{tabular}
    \end{center}

    \noindent shows this clearly.

To omit indentation in the entire document put `\setlength{\parindent}{0pt}` in the preamble. If you do that, you may want to also set the length of spaces between paragraphs, `\parskip` (see \parindent & \parskip).

Default LaTeX styles have the first paragraph after a section that is not indented, as is traditional typesetting in English. To change that, look on CTAN for the package `indentfirst`.

### `\parindent` & `\parskip`

Synopsis:

    \setlength{\parskip}{horizontal len}
    \setlength{\parinden}{vertical len}

Both are a rubber lengths (see Lengths). They give the indentation of ordinary paragraphs, not paragraphs inside minipages (see minipage), and the vertical space between paragraphs.

This, put in the preamble,

    \setlength{\parindent}{0em}
    \setlength{\parskip}{1ex}

arranges that the document will have paragraphs that are not indented, but instead are vertically separated by about the height of a lowercase ‘`x`’.

In standard LaTeX documents, the default value for `\parindent` in one-column documents is `15pt` when the default text size is `10pt` , `17pt` for `11pt`, and `1.5em` for `12pt`. In two-column documents it is `1em`. The default value for `\parskip` in LaTeX’s standard document styles is `0pt plus1pt`.

### Marginal notes

Synopsis, one of:

    \marginpar{right}
    \marginpar[left]{right}

Create a note in the margin. The first line of the note will have the same baseline as the line in the text where the `\marginpar` occurs.

The margin that LaTeX uses for the note depends on the current layout (see Document class options) and also on `\reversemarginpar` (see below). If you are using one-sided layout (document option `oneside`) then it goes in the right margin. If you are using two-sided layout (document option `twoside`) then it goes in the outside margin. If you are in two-column layout (document option `twocolumn`) then it goes in the nearest margin.

If you declare `\reversemarginpar` then LaTeX will place subsequent marginal notes in the opposite margin to that given in the prior paragraph. Revert that to the default position with `\normalmarginpar`.

When you specify the optional argument left then it is used for a note in the left margin, while the mandatory argument right is used for a note in the right margin.

Normally, a note’s first word will not be hyphenated. You can enable hyphenation there by beginning left or right with `\hspace{0pt}`.

These parameters affect the formatting of the note:

`\marginparpush`

  Minimum vertical space between notes; default ‘`7pt`’ for ‘`12pt`’ documents, ‘`5pt`’ else.

`\marginparsep`

  Horizontal space between the main text and the note; default ‘`11pt`’ for ‘`10pt`’ documents, ‘`10pt`’ else.

`\marginparwidth`

  Width of the note itself; default for a one-sided ‘`10pt`’ document is ‘`90pt`’, ‘`83pt`’ for ‘`11pt`’, and ‘`68pt`’ for ‘`12pt`’; ‘`17pt`’ more in each case for a two-sided document. In two column mode, the default is ‘`48pt`’.

The standard LaTeX routine for marginal notes does not prevent notes from falling off the bottom of the page.