A Blockchain Notary is a Cryptographic Digest
The purpose of this action is to file a document on the
blockchain, and have a time-linked historical reference to it. Technically, a document can include government typified paperwork, high-pixel film, or even a region-marked photograph or piece of artwork.
Bitcoin.com’s website put it this way, “A cryptographic digest of your document will be stored in the bitcoin blockchain, linking it to the time of submission. Your document could be anything, from an input-constrained form like conventional government documents to a full-resolution movie or location-stamped image.”
Trustless Document Storage at Bitcoin.com
Having a document trustlessly inscribed on the blockchain has several benefits. The primary benefit is that documents are backed on the blockchain in perpetuity. This means that the document’s footprint exists in cyberspace even if the physical copy vanishes.
However, this also implies that the document stored will never be exposed. Its contents are not displayed via the blockchain. It is merely “dated” and cryptographically recorded, in which case its existence can be proven when necessary.