example to be used in the wikibook about LaTeX. The picture of the gull is one of Commons featured pictures Image:Gull portrait ca usa.jpg. In order to create it, first I downloaded the picture in a folder and I renamed it gull.jpg, then I created a tex file called figure_ref.tex and I put the following code in it:

\documentclass[a4paper,12pt]{article}

\usepackage[english]{babel}
\usepackage{graphicx}

\begin{document}

\begin{figure}
  \centering
    \includegraphics[width=0.5\textwidth]{gull}
  \caption{Close-up of a gull}
  \label{gull}
\end{figure}

Figure \ref{gull} shows a photograph of a gull.
\end{document}