Latex beamer and blocks

Block

\begin{frame}
\frametitle{Portable Object (PO) files}
\begin{block}{Nature}
\begin{itemize}
\item It's a raw, untranslated file
\item Created automatically using gettext package
\item Ready to be translated
\end{itemize}
\end{block}
\end{frame}

produce this :




Alertblock

\begin{frame}
\subsection{gettext}
\frametitle{gettext}
\begin{alertblock}{gettext in short}
\begin{itemize}
\item Part of GNU packages
\item Enables internationalization of software
\item Enables the creation of Portable Object (PO) file
\end{itemize}
\end{alertblock}
\begin{center}
\alert{\emph{Portable Object?}}
\end{center}
\end{frame}

produce this :




Exampleblock

\begin{frame}
\frametitle{Machine Object (MO) files}
\begin{exampleblock}{Description}
\begin{itemize}
\item \alert {Compiled file}, derived from PO
\item It's a binary, thus \emph{machine readable}
\end{itemize}
\end{exampleblock}
\end{frame}

produce this:



Good luck !