The link
The ordinary recipient link ends with #sidc_… — the key sits after “#”, which a browser never sends to a server. It stays out of server logs and out of what other sites learn when someone clicks onward. That is also why a messenger can't show a preview of it.
The permanent link
…/short/ followed by 16 characters. The key is the address itself, so messengers and social sites can unfold it into a card with a title, a description and an image. It is not secret, it is unguessable: whoever has it gets in.
The card shows only what you wrote for it (Settings → Behavior → Link preview) and your logo or the image you uploaded for it — never a photo from the gallery. Search engines are asked not to index it.
Side by side
- Who it's for — the link: one person or a family; the permanent link: anyone who sees the post.
- What it opens — the same albums under the same rules — it is one access with two addresses.
- Revoking — separately: revoking the permanent link leaves the link working; revoking the link takes its permanent link with it.
- Details before download — on a permanent link every device is asked on its own, so one person's name doesn't speak for everyone.
- Password — works on both: the permanent link asks for the link's password.
How to get one
- When creating a link: tick “Also create a permanent link for social media”.
- Later: Shares → the link's menu → “Create permanent link”; the same menu copies or revokes it.
- Permanent links are part of the Simple plan and above.