-The https://lttng.org/[_Linux Trace Toolkit: next generation_] is an open
-source software package used for correlated tracing of the Linux kernel,
-user applications, and user libraries.
+include::common-intro.txt[]
+
+An LTTng relay daemon, `lttng-relayd`, is a program which receives trace
+data from (possibly remote) LTTng session/consumer daemons and which
+writes it to the local file system. The relay daemon also accepts LTTng
+live connections from compatible readers (for example,
+man:babeltrace2(1)); this is the recommended approach to read trace data
+while the remote tracing session is active.
+
+By default, a relay daemon listens on all network interfaces to receive
+trace data, but only on `localhost` for LTTng live connections. Override
+the listening URLs with the option:--control-port, option:--data-port,
+and option:--live-port options (see the <<url-format,URL format>>
+section below). For example, use the
+option:--live-port=+tcp://0.0.0.0:{default_network_viewer_port}+ option
+to make a relay daemon listen to LTTng live connections on all network
+interfaces.