LISTEN           UNIT                            ACTIVATES
/dev/initctl     systemd-initctl.socket          systemd-initctl.service
/dev/log         systemd-journald.socket         systemd-journald.service
...
[::]:19531       systemd-journal-gatewayd.socket systemd-journal-gatewayd.service
kobject-uevent 1 systemd-udevd-kernel.socket     systemd-udevd.service

17 sockets listed.
Pass --all to see loaded but inactive sockets, too.