ZNC is an "IRC bouncer". it is some software that allows you to seemingly stay connected on IRC chat and also hide your IP, but really go offline with your actual machine. ZNC will buffer everything for you, when you physically go online again later.
There are some free ZNC servers, but their "terms" are 100% outrageous, so there is high demand for a new fair free ZNC server.
the landing site znc.In is famous for their worthless documentation such as "The prefix for the status and module queries". Nobody makes any sense of this cryptic blabber.