How to add public comments to transactions?

[K~Ehleyr]

Something that's puzzled me since forever but I never got around to asking.... Sometimes when viewing transactions on blockchain.info, some transactions have public comments beside them, like "payout to Joe Bloggs" or "Merry Christmas".  How do they get there?  If I want to send somebody some bitcoin with the comment "Happy birthday", how do I do it?  Can it be done from Bitcoin Core wallet?

[achow101]

Those comments are not actually part of the transaction. They are part of blockchain.info's database. You won't see those comments anywhere else except on blockchain.info.

[K~Ehleyr]

Ahhhh thank you!!  That explains why I couldn't figure out how to do it 

[rytyr]

Wasn't it possible to add message via payment protocol ( it was something like BIP 70 ) in the past, was it?
I personally have never tried it, but when I got into Bitcoin I read a book where the author said that it is possible.
I am not sure but I think it was Mastering Bitcoin. I read three Bitcoin books so I need a little time to figure out which one it was.

[Velkro]

Wasn't it possible to add message via payment protocol ( it was something like BIP 70 ) in the past, was it?

Indeed i think same thing. I heard this before, one thing i know for sure its very complicated to include actual message to blockchain as transaction(s) but its possible. Its not plainly visible from what i think tho, it need to be decoded first.