This method of requiring miners to use machines and spend time and energy trying to achieve something is known as a proof-of-work system and is designed to deter malicious agents from spamming or disrupting the network.Whoever successfully unlocks the next block is rewarded with a set number of bitcoin known as “block rewards” and gets to add a number of transactions to the new block. They also earn any transaction fees attached to the transactions they add to the new block. A new block is discovered roughly once every 10 minutes.