PoW is the acronym for Proof-of-Work.
Proof-of-Work is an algorithm used in distributed cryptocurrency networks for reaching consensus; and is the first successful mechanism that solved the double-spending problem for digital finances.
The concept of PoW is based on the principles of fair governance and open participation. PoW is the mechanism predominantly used in public networks due to its minimal requirements of having a dedicated piece of hardware; such as a GPU or ASICS machine.
Nodes in Proof-of-Work environments are called Miners. Miners compete with one another in an attempt to solve a hash puzzle, the resolution of which give the solving participant the right to publish the next block of network activity/transactions. Blocks are chronologically ordered by their height and reference.
PoW environments are sometimes semantically referred to as “longest-chain rules”, whereby new blocks can only be appended to the longest version of the blockchain.
Because Proof-of-work is computationally intensive, it provides a robust security guarantee and in turn likelihood of validity for its economic activity. However that computational intensity also translates to a large carbon footprint (energy consumption).