Backends

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{imakeidx}
\makeindex
\begin{document}
\section{Introduction}
In this example several keywords\index{keywords} will be used
which are important and deserve to appear in the Index\index{Index}.

Terms like generate\index{generate} and some\index{others} will
also show up.

\printindex
\end{document}