You may have seen people making a presentation in beamer and showing slides progressively, pressing enter each time they want to show a new element. This is the most used feature of slide presentation programs, and of course beamer offers you a way to emulate it using beamer overlays.

Pause, one of beamer overlay commands to show elements one by one!

The following illustrative example shows how to uncover elements of a list one by one using the pause command:

% Beamer pause command
\documentclass{beamer}

\usetheme{EastLansing}

\begin{document}

\begin{frame}{What is Pause in Beamer?}

The \textbf{trajectory} of a switched system in steady state reflects:

\begin{itemize}
    \item The switching frequency;
\pause
    \item The spent time in each subsystem;
\pause
    \item The number of subsystems used;
\pause 
    \item and the succession of these subsystems.
\end{itemize}

\end{frame}

\end{document}

Compiling this code yields to 4 slides showing the list elements one by one:

Beamer has much more to offer in this aspect, especially using overlay specifications, that offer you an incredible amount of possibilities. If you are interested on a more thorough tutorial on beamer overlays, you can find it here.