In the Library sidebar, collections.

Six of them here: Entertainment, My Images, Nature, News, Quotes, Study, each with its count beside it.

The heading carries its own note: across Spaces.

A Collection is the one grouping that ignores which Space you are standing in.

Add one from a card's menu.

Add to collection, then pick.

An item sits in one Collection at a time, so on something already filed the wording reads move to collection.

A tag is lighter.

Tag, an input reading add tag, Enter to commit.

Type Writing Craft and what lands is writing dash craft: lowercased, with spaces and punctuation turned into dashes so it stays tidy.

A Collection asks where this belongs, and takes one answer.

A tag asks what to call it, and takes as many as you like.

One thing to know before you go looking.

Collections stay yours: sharing works at the level of a single item, with a code and a passphrase.

Six shelves you built, and a flat layer of labels running across all of them.