\documentclass[a4paper,12pt,twocolumn]{article}

\input{header}

\title{If only people were kinder to one another}
\author{Ambroise Croizat}
\date{}

\begin{document}

\maketitle

\begin{abstract}
It is not very fun writing an abstract for a template.
\end{abstract}

\input{introduction}

\printbibliography

\end{document}