Meanings of the navigation symbols in beamer

Question

When compiling a beamer tex source file, I have a pdf with a progress bar. But I'm not sure the function of each icon. What are they for? How to remove them?

\documentclass{beamer}
\title{Hello}
\author{Samuel}
\date{\today}

\begin{document}
\begin{frame}{}{}
    \maketitle
\end{frame}

\section{section}

\begin{frame}{The subtitle}{}
    What is your name? \ldots
    \begin{enumerate}
        \item A \emph{Hello} $x + y == z$
        \item B $\sin (x) + \cos(x)$
    \end{enumerate}
\end{frame}
\end{document}