Bitcoin Forum

First time poster here. I've been noticing so many projects using blockchains, but I don't understand how is proof of work applicable to most applications. Do they all use it? Is it necessary?

Edit: What do you call this category for proof of X?

Not all of them use proof of work (POW), there are also delegate proof of stakes (DPOs), proof of stakes (Pos), proof of burn (POB) and so on. For more information, you can find the answer use google search.

there is no necessary indeed, POW cost a lot of energy, its unfriendly to the environment, most new coin dont use POW now

No, some important ones are proof of stake (pos) where the stake (the amount they have) of people is vital in the system. I'm not sure, but I think waves is a pos instance. I think ethereum will integrate pos system into its regulation soon as well.

That is right, POW will cost a lot of energy, such as the ETH and BTC are in this mode, but the ETH will turn to POS maybe at the end of this year according to the plan.

Since nobody has answered your edit, this "category" you are looking for is called a "consensus algorithm", specifically when used to describe the system used in cryptocurrency blockchains to reach consensus. Proof of work is the most popular but you can see many new concepts coming up nowadays like proof-of-human and proof-of-time even.

Is it necessary for a given blockchain to have a consensus algorithm? Is that the only way to create trust in a distributed environment like a blockchain? I'm assuming this means you can theoretically apply multiple consensus algorithms to a blockchain to have multiple signals for verification/trust right?

The entire point of bitcoin/blockchain is that it is *trustless*. If you need to trust something, just use visa.

If you are really interested, the following document presents nearly all known consensus algorithms actually in use for blockchains. It does also cover some algorithms for private and "consortium" blockchains.

Untangling Blockchain: A Data Processing View of Blockchain Systems (https://128.84.21.199/pdf/1708.05665.pdf)

Here is a short list of coins and the major consensus methods they use.

PoW - Bitcoin and all clones, Litecoin, Dogecoin, Viacoin
PoS - Reddcoin, Blackcoin, Peercoin, Spectrecoin
PoW/PoS - Decred, Deep Onion
DPoS - Waves
Proof of Importance - NEM
Proof of Signature - Xtrabytes
Proof of Burn - Counterparty
Directed Acrylics Graphs - Iota, Byteballs
Byzantine Fault Tolerance - Neo (formerly Antshares)

This is a good list to search for potential investments.

The trust is just displaced. You are trusting the consensus algorithm, and in case of bitcoin that's the PoW.


Thanks

There is even a proof of time coming out - Chronology

Not equivalent; when you put money in your bank, you trust the bank *and* the currency. With bitcoin, you just trust the currency, which is the minimal level of trust possible.

POW and POS are the most popolar  algo. You can use google to know them if you want to involve in crypto.

Some remarks to CoinCollector006's list:

Peercoin is PoW/PoS, although PoW blocks do not really add security because chain trust (the "longest chain" rule) depends only on PoS. In Novacoin (a Peercoin clone) and its clones, the chain trust depends on PoW _and_ PoS.

Proof of Importance is actually Proof of Stake with the addition of stake being "weighted" by the transactions the node does.

I've briefly looked into this and it seemed to be a variation of the "Byzantine Fault Tolerance" algorithm. The same is also true for DPoS. I would group "DpoS", BFT and Proof of Signature together.

This one is wrong - Counterparty is a layer on top of Bitcoin, Proof of Burn in CP is a method to distribute new coins but not a "block reward". Proof of Burn is only used by Slimcoin as a part of the consensus method.

because most of the new coins are assets that has built based on the blockchain in others coin. but such as decent already built in the its blockchain technology without use the pow.
I just take take the decent as an example the project that has built non pow blockchain.

You're not drawing a parallel comparison. It's more appropriate to say, "when you put money in your blockchain, you trust the blockchain *and* the currency." I understand your point regardless 👍