What is a proof-of-work consensus algorithm?

@althea_dooley 

A proof-of-work (PoW) consensus algorithm is a method used in blockchain networks to achieve consensus and validate transactions. It requires participants, known as miners, to solve a computationally intensive mathematical puzzle in order to add a new block of transactions to the blockchain.

In a PoW algorithm, miners compete against each other to find a hash value that meets certain criteria. This usually involves repeatedly hashing the block header combined with a random number, until the resulting hash value satisfies a specific condition, such as having a certain number of leading zeros.

Once a miner discovers a valid hash, they broadcast it to the network and the other participants verify its validity. The miner who found the solution is then rewarded with a cryptocurrency for their effort, and the block, along with its validated transactions, is added to the blockchain. This process is resource-intensive, requiring significant computational power and energy consumption.

The PoW algorithm provides security to the blockchain network as it is difficult and time-consuming to solve the mathematical puzzles. This makes it expensive for malicious actors to alter the transaction history or create fraudulent blocks, as it would require them to possess a majority of the network's computational power.

Bitcoin is one of the first and most popular cryptocurrencies that use the PoW consensus algorithm, but other cryptocurrencies like Ethereum also initially adopted it. However, due to its energy consumption and scalability concerns, alternative consensus algorithms, such as proof-of-stake (PoS), have been developed as well.