This is what I got immediately after pressing return after entering nc
www.facebook.com
nc: missing hostname and port
usage: nc [-46AacCDdEFhklMnOortUuvz] [-K tc] [-b boundif] [-i interval] [-p source_port]
[--apple-recv-anyif] [--apple-awdl-unres]
[--apple-boundif ifbound]
[--apple-no-cellular] [--apple-no-expensive]
[--apple-no-flowadv] [--apple-tcp-timeout conntimo]
[--apple-tcp-keepalive keepidle] [--apple-tcp-keepintvl keepintvl]
[--apple-tcp-keepcnt keepcnt] [--apple-tclass tclass]
[--tcp-adp-rtimo num_probes] [--apple-initcoproc-allow]
[--apple-tcp-adp-wtimo num_probes]
[--setsockopt-later] [--apple-no-connectx]
[--apple-delegate-pid pid] [--apple-delegate-uuid uuid]
[--apple-kao] [--apple-ext-bk-idle]
[--apple-netsvctype svc] [---apple-nowakefromsleep]
[--apple-notify-ack] [--apple-sockev]
[--apple-tos tos] [--apple-tos-cmsg]
[-s source_ip_address] [-w timeout] [-X proxy_version]
[-x proxy_address[

ort]] [hostname] [port
]