+ <option>Accept=true</option> is set, a service
+ template file <filename>foo@.service</filename> must
+ exist from which services are instantiated for each
+ incoming connection.</para>
+
+ <para>Unless <varname>DefaultDependencies=</varname>
+ is set to <option>false</option>, socket units will
+ implicitly have dependencies of type
+ <varname>Requires=</varname> and
+ <varname>After=</varname> on
+ <filename>sysinit.target</filename> as well as
+ dependencies of type <varname>Conflicts=</varname> and
+ <varname>Before=</varname> on
+ <filename>shutdown.target</filename>. These ensure
+ that socket units pull in basic system
+ initialization, and are terminated cleanly prior to
+ system shutdown. Only sockets involved with early
+ boot or late system shutdown should disable this
+ option.</para>
+
+ <para>Socket units will have a
+ <varname>Before=</varname> dependency on the service
+ which they trigger added implicitly. No implicit
+ <varname>WantedBy=</varname> or
+ <varname>RequiredBy=</varname> dependency from the
+ socket to the service is added. This means that the
+ service may be started without the socket, in which
+ case it must be able to open sockets by itself. To
+ prevent this, an explicit <varname>Requires=</varname>
+ dependency may be added.</para>
+
+ <para>Socket units may be used to implement on-demand
+ starting of services, as well as parallelized starting
+ of services. See the blog stories linked at the end
+ for an introduction.</para>
+
+ <para>Note that the daemon software configured for
+ socket activation with socket units needs to be able
+ to accept sockets from systemd, either via systemd's
+ native socket passing interface (see
+ <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ for details) or via the traditional
+ <citerefentry><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>-style
+ socket passing (i.e. sockets passed in via standard input and
+ output, using <varname>StandardInput=socket</varname>
+ in the service file).</para>