Bitcoin, The most famous cryptocurrency that you would surely have heard of is a digital currency invented by a person with the alias Satoshi Nakamoto in 2009. I like to consider Bitcoin as a digital gold/virtual asset which uses peer-to-peer technology to facilitate payments.
Bitcoin was invented to eliminate the need for the middlemen like banks and governments and provide an alternative, decentralized method to send and receive money.
A consensus mechanism is a fault-tolerant mechanism that is used in computer and blockchain systems to achieve the necessary agreement on a single data value or a single state of the network among distributed processes or multi-agent systems, such as with cryptocurrencies.
Bitcoin works on a Proof Of Work consensus algorithm.
POW is a consensus algorithm responsible for validating new transactions and adding them to the blockchain.
Miners use their computational power in the form of "Work" in order to solve complex puzzles.
The one who is successful in solving the puzzle gets a chance to verify and add a transaction into the block.