IRC user modes explained

Channel modes moderate rooms; user modes configure you. They are set on your own nick — /mode yournick +i — and only you (and the server) can set them. /mode yournick with nothing else shows your current modes.

The ones you'll actually meet #

+i — invisible. Confusingly named: you are perfectly visible in any channel you share with someone. What it hides is your presence from global /who and /names queries by strangers, making nick-harvesting harder. Many networks set it by default, and you should leave it on.

+x — host cloaking (on networks that implement it as a user mode). Hides your real hostname behind a network-issued cloak. On Libera.Chat cloaks are instead assigned through services or staff, but the effect is the same: your home IP is not on display in every /whois.

+w — wallops. Opt-in to network-wide operator notices. Mostly of historical and curiosity value; expect maintenance notes and occasional drama.

+Z / +z — TLS marker. Set automatically when you connected over TLS. You cannot set it yourself; its presence in /whois is how others can verify your connection is encrypted to the server. Some channels even require it via a channel mode that admits only TLS users.

+R — registered-only PMs (network-dependent letter). Blocks private messages from unidentified users — the single best anti-spam switch on networks that offer it. If you ever receive a wave of spam PMs, this is the fix, alongside registering and identifying.

+g — caller ID (some networks). Even stricter: all PMs are blocked unless you whitelist the sender with /accept nick.

+D / +d — deaf modes (ircd-specific): receive no channel messages — used by bots that only need to send.

What user modes are not #

They are not per-channel: those prefixes you see (@, +) are channel statuses (+o, +v set on the channel, explained here), not user modes. And operator status of the network (+o as a user mode) is gained with /oper, credentials required — being an IRC operator is a job, not a setting.

A sensible default set #

For a normal user on a modern network: +i on (usually already is), cloak arranged if the network offers one, connect over TLS so +Z appears, and turn on the registered-only-PM mode the first time spam finds you. Everything else is optional color. The exact letters vary by IRCd, so check your network's user-mode documentation — and when the letters disagree with this article, the network is right.