Proof-of-Publication (PoP)

From CryptoWiki

"Putting data on the blockchain is a so-called proof-of-publication. If you need to prove that some data was available to everyone in the world at some point, you can put it in the blockchain. But typically when people think they need to do this, what they really need to do is anchor their data to the chain. There are some use cases where you really need proof-of-publication but it's much more rare."