Package geometry parameters and changing left margin

Question

I want to make an indented paragraph, that is to indent the whole paragraph and not just the first line as happens with \par. I use geometry, so I thought that package might have a parameter that regulates the indent. I read through the .log file of my document and found:

\Gm@cnth=\count186
\Gm@cntv=\count187
\c@Gm@tempcnt=\count188
\Gm@bindingoffset=\dimen277
\Gm@wd@mp=\dimen278
\Gm@odd@mp=\dimen279
\Gm@even@mp=\dimen280
\Gm@layoutwidth=\dimen281
\Gm@layoutheight=\dimen282
\Gm@layouthoffset=\dimen283
\Gm@layoutvoffset=\dimen284
\Gm@dimlist=\toks36

Seeing as I couldn't guess what these were, I came here. I looked at this question and this other one, so I found \hoffset, but opening a group and changing that seemed to have no effect. Same goes for \Gm@layouthoffset. Typing:

{\makeatletter\Gm@lmargin=2pt
foo bar baz
\makeatother \\
}

with a \\ just before the { makes the foo bar baz typeset, but instead of changing the parameter prints out 113.81102pt=2pt. So the question is: what are those parameters, how do I use them, can I use them to indent the paragraph as I want, and if not how do I?

Answer 1

The package geometry is surely not what you're looking for. The pagination parameters are relevant only when the page is shipped out, the only one that's relevant during typesetting is \textwidth, but it's better not to tamper with it.

The changepage packages provides the adjustwidth environment:

\documentclass{article}
\usepackage{changepage}
\usepackage{lipsum}
\begin{document}
\lipsum[1]
\begin{adjustwidth}{1cm}{0cm}
\lipsum[2]
\end{adjustwidth}
\lipsum[3]
\begin{adjustwidth}{1cm}{1cm}
\lipsum[4]
\end{adjustwidth}
\end{document}

You might also look at the quoting package.

Note that, while setting \leftskip may seem to work, it is not compatible with lists in the indented material.

Answer 2

\documentclass{article}
\usepackage{blindtext}    
\newenvironment{mypar}
  {\par\leftskip=2cm}
  {\par}

\begin{document}
\blindtext
\begin{mypar}
\blindtext
\end{mypar}
\blindtext

\end{document}