Well that's precisely what I have issue with.

No I don't think a "blockchain" is merely a public database nor that git is a "blockchain". The term "blockchain" was initially defined as the proof-of-work data structure that Bitcoin uses to store transactions and its definition was later slightly expanded to describe that same data structure used in other cryptocurrencies. If it now just means "public database" then we've lost a useful word.

> Git is a Blockchain. Do you think that git is useless?

Git also uses merkle trees but the similarity pretty much ends there.

Proof of work is merely one form of consensus algorithms.

There are many forms of consensus algorithms.

> Git also uses merkle trees

Blockchains are not a complicated concept. They are merely a merkle tree combined with a consensus algorithm. That's it.

People try to make these concepts way more complicated than they actually are. A lot of this crypto stuff is actually quite simple.

It was the only one at the time. Since then a few alternatives have been proposed but none that rival PoW, at least in terms of security.

> Blockchains are not a complicated concept. They are merely a merkle tree combined with a consensus algorithm. That's it.

I wouldn't say so, the block chain is a chain, not a tree. Actually, the use of merkle trees to represent transaction data is an implementation detail. Bitcoin would have worked fine without them (though "lightweight" clients would have suffered a bit).

I second that it's a simple concept though.