Text, voice, forum, announcement, and stage channels, organized into categories: created, renamed, moved, and kept in sync. Rename anything and Packet re-points every reference automatically. (Configure → Channels.)
Drag a channel to reorder it, or drag it into a category to move it. A rename changes the channel or category you already have, so its messages and settings stay. Remove a category and its channels stay too, just without a category. Each channel carries its own settings: a topic, an NSFW mark for an age-restricted channel, and a slowmode. Text channels add a slowmode for new threads, and text and announcement channels add Hide idle threads after. Voice and stage channels add a Bitrate and a Region, and voice channels a Member limit and Video quality. Leave a box blank and Packet leaves that setting as it is in Discord. A forum's own settings are under Forums. An existing text channel can switch to announcement and back, and Packet converts the channel you have rather than making a new one.
Who can see what. Open a channel's or a category's Overwrites to allow, deny or leave neutral each permission for a role, or for one person by user ID. Deny View Channel to @everyone and the channel shows as private. A channel with no overwrites of its own follows its category. Give it some and it has its own, unless you tick Merge with category, which keeps the category's overwrites and lays the channel's on top. A permission preset can stand in for a set of boxes.
A channel Packet can't see is never changed, and the Plan says how many it left alone. In Full mode a channel you take out of the blueprint is archived rather than deleted, as How Packet works explains.