One often requires that the abstract of a paper should appear across the entire page, even in a two-column paper. The required trick is:
\documentclass[twocolumn]{article}
...
\begin{document}
... % \author, etc
\twocolumn[
\begin{@twocolumnfalse}
\maketitle
\begin{abstract}
...
\end{abstract}
\end{@twocolumnfalse}
]
Unfortunately, with the above \thanks won't work in the
\author list. If you need such specially-numbered footnotes, you
can make them like this:
\title{Demonstration}
\author{Me, You\thanks{}}
\twocolumn[
... as above ...
]
{
\renewcommand{\thefootnote}%
{\fnsymbol{footnote}}
\footnotetext[1]{Thanks for nothing}
}
and so on.
As an alternative, among other facilities the abstract package
(available from macros/latex/contrib/supported/abstract.tar.gz) provides a
\saythanks command and a onecolabstract environment
which remove the need to fiddle with the \thanks and
footnoting. They can be used like this:
\twocolumn[
\maketitle % full width title
\begin{onecolabstract} % full width abstract
... text
\end{onecolabstract}
]
\saythanks % typeset any \thanks