Cryptocurrencies are digital systems (protocols) for exchanging value between participants on a decentralised computer network. Bitcoin (BTC) is the most famous and widely-adopted cryptocurrency. 

Most cryptocurrencies use hard-to-solve cryptographic puzzles called “Proof of Work” to secure the operation of the network. The process of verifying the cryptographic solutions is commonly referred to as “mining”. Bitcoin introduced a “reward” system, where the miner who solves a block is awarded a small amount of the cryptocurrency.
This reward compensates the miner for contributing their hardware and electricity to the mining network.

The solution of a block is a vital operation to allow distributed consensus and add the block to the blockchain.

Technology-rooted movements like Bitcoin have demonstrated, through the power of the default, consensus mechanisms, and voluntary respect of the social contract, that it is possible to use the internet to make a decentralised value – transfer system, shared across the world and virtually free to use. This system can be said to be a very specialised version of a cryptographically secure, transactionbased state machine.