Proof of Work (PoW) is a consensus algorithm used in blockchain networks to validate transactions and secure the network. The main idea behind PoW is to require network participants, known as miners, to solve complex mathematical problems in order to add new blocks to the blockchain.

When a miner successfully solves a puzzle, they broadcast the solution to the rest of the network, and other participants can easily verify the solution to ensure it is correct. Once a solution is verified, the miner can add a new block to the blockchain, which contains a list of verified transactions along with a unique cryptographic hash that links the block to the previous block in the chain.

The puzzle that miners solve is intentionally difficult and time-consuming, which ensures that miners must expend a significant amount of computational effort in order to add a new block to the blockchain. In order to solve the puzzle, miners use specialized hardware that is designed to perform many calculations in parallel, which can require a lot of energy.

The difficulty of the puzzle is regularly adjusted to maintain a consistent rate of new blocks being added to the blockchain. This helps to prevent the network from being overwhelmed with too many or too few transactions being verified at any given time.

Overall, Proof of Work is an effective way to secure a blockchain network and prevent fraudulent transactions, but it is also resource-intensive and can be slow. As a result, alternative consensus algorithms such as Proof of Stake are being developed that aim to provide similar levels of security with less computational effort.

Proof of work ensures the security of a blockchain by making it expensive to attack or manipulate the network. It allows for secure peer-to-peer transaction processing without needing a trusted third party. The technique verifies the accuracy of new transactions that are added to a blockchain, ensuring the integrity of new data. By requiring miners to perform complex calculations, proof of work disincentivizes attacks on a crypto's blockchain. 

The algorithm used by Bitcoin adjusts the difficulty of mining depending on how much computing power is being used, making it more difficult and expensive to manipulate the network. However, proof-of-work has some flaws and limitations that have led some cryptocurrencies to explore alternative consensus mechanisms such as proof-of-stake.