diff --git a/chapters/ch04-system.tex b/chapters/ch04-system.tex
index b2a4327..549e0d2 100644
--- a/chapters/ch04-system.tex
+++ b/chapters/ch04-system.tex
@@ -174,6 +174,8 @@ alsa-base/jammy,jammy,now 1.0.25+dfsg-0ubuntu7 all [installed,automatic]
 […snip]
 \end{Verbatim}
 
+Again, that's a lot of information, but \texttt{[installed]} means that this package was installed manually, and \texttt{[installed,automatic]} means that it was installed as a dependency of some other package.\index[concepts]{dependencies}
+
 Unfortunately, that will give you a list of \texttt{every} packaged that has been installed on your system, including from when you installed Linux originally. To get a list of manually installed applications, use
 
 \begin{Verbatim}[frame=lines]