diff --git a/Manuals/Tcpi-ug/Preface.docbook b/Manuals/Tcpi-ug/Preface.docbook
index a7bfd2f..c071b9c 100755
--- a/Manuals/Tcpi-ug/Preface.docbook
+++ b/Manuals/Tcpi-ug/Preface.docbook
@@ -17,12 +17,24 @@
     </para>
 
     <para>
-        To implement the configurations described in this book, you
-        need computers, modem devices, switches (optional), a
-        telephone network and need for sharing information with your
-        friends.
+        To implement the configuration described in this book, you
+        need two or more computers connected to the telephone network
+        of your country by mean of modem devices. Optionally, to
+        extend the entire network, you could use Ethternet devices to
+        create local area networks (LANs) on both ends of each
+        connection established over the telephone network able of
+        exchanging data between themselves. For example, consider an
+        infrastructure where you have one LAN for each province in
+        your country and then, each of these LANs are connected using
+        the country's telephone network. Each LAN would have one or
+        more server computers to concentrate the information produced
+        by that province and then, using the telephone network, each
+        server computer would be able of exchanging data between
+        themselves.  This infrastructure would be as expensive as a
+        national telephone call would be (without counting the
+        electrical power consume required by computers, of course).
     </para>
-    
+
     <para>
         To make the information of this book managable, it has been
         organized in the following parts:
@@ -31,12 +43,17 @@
     <itemizedlist>
     <listitem>
     <para>
-        <xref linkend="connectivity" /> describes ...
+        <xref linkend="connectivity" /> describes how to link
+        computers in order to make internet services described in
+        <xref linkend="services" /> available to other computers.
     </para>
     </listitem>
     <listitem>
     <para>
-        <xref linkend="services" /> describes ...
+        <xref linkend="services" /> describes how to configure
+        computers to provide internet services and also exchange
+        information between computers using the media described in
+        <xref linkend="connectivity" />.
     </para>
     </listitem>
     <listitem>