\documentclass{article}
\begin{document}
\section{Itemize}
\begin{itemize}
  \item One\label{it:one}, but not \ref{en:one}
  \item Two\label{it:two}, but not \ref{en:two}
  \item Three\label{it:three}, but not \ref{en:three}
\end{itemize}

\section{Enumerate}
\begin{enumerate}
  \item One \label{en:one}, but not \ref{de:one}
  \item Two \label{en:two}, but not \ref{de:two}
  \item Three \label{en:three}, but not \ref{de:three}
\end{enumerate}

\section{Description}
\begin{description}
  \item[One] \label{de:one}, but not \ref{it:one}
  \item[Two] \label{de:two}, but not \ref{it:two}
  \item[Three] \label{de:three}, but not \ref{it:three}
\end{description}

\section{Nested Enumerate}
\begin{enumerate}
  \item One
\begin{enumerate}
  \item One
  \item Two
  \item Three
\end{enumerate}
  \item Two
\begin{enumerate}
  \item One
  \item Two
  \item Three
\end{enumerate}
  \item Three
\begin{enumerate}
  \item One
  \item Two
  \item Three
\end{enumerate}
\end{enumerate}

\section{Spacing}
Taller:
\begin{itemize}
\itemsep=2em
\item a
\item b
\item c
\end{itemize}

Taller \& Taller:
\begin{itemize}
\item a
\itemsep=2em
\item b
\itemsep=3em
\item c
\end{itemize}

{\itemsep=2em
Itemsep outside has no effect:
\begin{itemize}
\item a
\item b
\item c
\end{itemize}}

\section{Mixed tags}
\begin{itemize}
\item a
\item b
\item[foo] bar
\item c
\end{itemize}

\begin{enumerate}
\item a
\item b
\item[foo] bar
\item c
\end{enumerate}

\section{Generalized Lists}
\begin{list}{$\star$}{}
   \item First item.
   \item Second.
   \item[foo] bar
   \item And the third.
\end{list}

\newcounter{exer}

\begin{list}{\textbf{\thesection \ - \theexer}}{\usecounter{exer}}
   \item First item.
   \item Second.
   \item[foo] bar
   \item And the third.
\end{list}

\end{document}
