Sealing takes any text — a post, a letter, a contract, your profile — and locks a fingerprint of it into a permanent, tamper-evident chain with an exact timestamp. From that moment, anyone can prove the words haven't been changed since. No account, no trust required: it's maths you can check yourself.
The point isn't secrecy. The text can be completely public. The point is that nobody can quietly change it after the fact, and nobody has to take your word that they didn't.
Public seal: the details are stored and anyone can see them when they check. Right for things you want verifiable — your identity, a published notice, a price list.
Private seal: only the fingerprint is sealed. The content never leaves your device and is never stored. The chain just proves that a document with that exact fingerprint existed at that moment. You keep the original, and reveal it only if you ever need it as evidence — a contract, a sensitive letter. On the profile page, this is the "publish to public registry" tick box: untick it to seal privately.