Changing the style of a single section

Question

I'm trying to change the format of a single section in my document.

The section is the introduction of my document, and therefore, I don't want it to be numbered.

I tried to define a new command

\newcommand{\ssection}[1]{%
  \section[#1]{\centering\normalfont\scshape #1}}

it works, however, I can't suppress the numbering.

Answer 1

With the help of the titlesec package you can define a command containing the format for special section(s) and another one for regular section(s) and change the formatting as required:

\documentclass{article} 
\usepackage{titlesec}

\newcommand\specialsection{%
  \titleformat*{\section}{\centering\scshape\Large}
}
\newcommand\regularsection{%
  \titleformat{\section}{\normalfont\Large\bfseries}{\thesection}{1em}{}
}

\begin{document}

\specialsection
\section*{Introduction}

\regularsection
\section{A Test Section} 
\section{Another Test Section} 

\end{document}

Answer 2

You can use \section* to set an unnumbered section. However, this also removes it from the ToC. To reinsert it, use \addcontentsline{toc}{section}{<name>}, like in the following minimal example:

\documentclass{article}
\usepackage{lipsum}% http://ctan.org/pkg/lipsum
\begin{document}
\tableofcontents
\section*{Introduction}\addcontentsline{toc}{section}{Introduction}
\lipsum[1-10]
\section{Another section} \lipsum[11-20]
\section{Yet another section} \lipsum[21-30]
\end{document}

The same would hold for other document classes (like book and report).

lipsum was used to generate dummy text, Lorem Ipsum style.