What does making my profile public or private actually do?

Your profile has two visibility switches under Account → Edit profile, and they do different things.

Public profile

When your profile is public, other members can visit it and see the pieces and sets you've marked public. Your public collection shows up in the Gallery collector directory.

When it's private, your profile and collection are hidden from everyone else. You can still use the whole app normally — log pieces, track sets, build a wantlist — it's just for your eyes.

Searchable

The searchable switch controls whether you turn up in search results and the collector directory. You can be public but not searchable (people can reach your profile by direct link, but you won't surface in browse/search).

One catch for sellers

To list something for sale or trade, your profile has to be public — that's how buyers can see who they're dealing with. We'll ask for consent the first time. See How do I list a piece for sale or trade?

Individual pieces also have their own public/private flag — see What can I record about a piece?