Social
Your profile is you: display name, picture, and the posts and comments you write. Your channel is what you broadcast. One comes with every account, stream key already issued.
Profile and channel
The channel owns the stream key, chat with its moderators and emotes, VODs and clips with the retention setting governing them, and channel follows and subscriptions. That is also why its settings are in Studio while sign-in, privacy and your wallet are on your account: the first belong to the channel, the second to you.
Three relationships
Following a channel is one-way and about broadcasts: no approval, and the owner sees the count. Following a person is one-way and about writing: their posts come into your feed. Someone following your channel is not following your posts, and neither implies the other.
Friendship is mutual, by request and acceptance, and either side can end it silently. Most privacy defaults key on it. Blocking cuts the relationship from your side, and everything here is managed from your account. Channel-side follower numbers live in Studio → Metrics instead.
Status and presence
You can set a status: an emoji, a short line of text, or both. Neither part is required, and clearing them is the same as never having set one. Your friends see it beside your name wherever they see you listed. Nobody else does, and it does not appear on your public profile.
A mark next to a friend's name says how they are around: green for here, amber for away from the keyboard, and a red bar for do not disturb, which quiets the alerts that would otherwise pop up for them. Green falls to amber on its own after about ten quiet minutes, and the whole thing goes away a minute or so after their last window closes — treat it as a rough signal, not a precise one. A plain red dot means they are broadcasting, which takes precedence over all of it.
You choose yours from the account menu, including invisible, which shows you as offline to everyone while everything else keeps working. Nobody can tell that apart from your having closed the app, which is the point of it.
Being visible at all is a setting of its own, under privacy, separate from sharing what you are watching. Turning it off hides the mark and leaves your status text alone.
Direct messages
Three settings decide who can open a conversation with you: friends, people you follow, or open, which is where an account starts. Note the direction on the middle one: it means people you chose to follow, so it never opens your inbox to your own audience. Anyone who does not clear the setting is refused outright rather than held for review.
A first message from a non-friend arrives as a request to accept or decline, and declining tells the sender nothing. Between friends there is no request step. Messages can be replied to individually, conversations can be reported, and sending is rate-limited per account to make bulk messaging impractical.
A conversation can hold up to fifty people. The same setting decides who may start one with you, so nobody can pull you into a group unless they could already message you — and you are invited to it rather than placed in it, with the same accept or decline. You can leave a group at any time.
A group is the people in it. Nobody is added or removed after it starts; messaging a different set of people simply opens a different conversation, and writing to the same people again picks up the one you already have. If you left and someone writes to that group again, you are asked back, and you see it from that message on rather than everything said while you were away.
Limits
Friend requests, messages and reports all carry per-account limits, set where ordinary use never meets them. The live numbers are on Developers, which also lists the posting and voting limits.