\documentclass{beamer}
\usetheme{Frankfurt}
\usecolortheme{default}
\usepackage{hyperref}
\usepackage[utf8]{inputenc} % this is needed for german umlauts
\usepackage[english]{babel} % this is needed for german umlauts
\usepackage[T1]{fontenc}    % this is needed for correct output of umlauts in pdf

\begin{document}

\title{The title of your presentation}
\subtitle{A subtitle}
\author{Martin Thoma}
\date{25. March 2013}
\subject{Computer Science}

\frame{\titlepage}

% Show table of contents
\frame{
    \frametitle{Contents}
    \setcounter{tocdepth}{1}
    \tableofcontents
    \setcounter{tocdepth}{2}
}

%\AtBeginSection[]{
%    \InsertToC[sections={\thesection}]  % shows only subsubsections of one subsection
%}

\section{Introduction}
\subsection{A subsection!}
\begin{frame}{Slide title}
    Slide content
\end{frame}

\begin{frame}{Another title}
    Some text\\
    \uncover<2->{Uncover me on slide 2 (-)\\}
    \visible<3->{visible from slide 3 on (-)\\}
    \only<4->{only from slide 4 (-)\\} 
    \onslide<5->{on slide 5 and further (-)\\}
    \uncover<6>{Uncover me on slide 6 \\}
    \visible<7>{visible on 7\\}
    \only<8>{only on slide 8 \\} 
    \alt<8>{I am on slide 8\\}{I am not on slide 8\\}
    \onslide<9>{on slide 9\\}
\end{frame}

\begin{frame}{Third title}
    \begin{block}{Title}
        This is a block.
    \end{block}

    \begin{exampleblock}{my Title}
        This is an example block.
    \end{exampleblock}

    \begin{alertblock}{another Title}
        This is an alert block.
    \end{alertblock}
\end{frame}

\end{document}