The job of miners in a cryptocurrency-network is to confirm transactions by solving the blockchains. The more transactions made, the bigger the blockchains and that is why miners need to upgrade their equipment every now and then. After solving a blockchain a miner is rewarded with a number of tokens or just a fraction, it depends on the value of the cryptocurrency that he is mining and the difficulty of the blockchain.
What miners are doing with those huge computers and dozens of cooling fans is guessing at the target hash. Miners make these guesses by randomly generating as many "nonces" as possible, as fast as possible. A nonce is short for "number only used once," and the nonce is the key to generating these 64-bit hexadecimal numbers I keep talking about. In Bitcoin mining, a nonce is 32 bits in size--much smaller than the hash, which is 256 bits. The first miner whose nonce generates a hash that is less than or equal to the target hash is awarded credit for completing that block, and is awarded the spoils of 12.5 BTC.
Around 2008, Satoshi Nakamoto founded Bitcoin. At the time, a paper was published through the Cryptography Mailing List. The first Bitcoin software client was released in 2009, and he collaborated with many other developers on the open-source team, careful never to reveal his identity. By 2011, the enigmatic Bitcoin founder had disappeared. His peers understood how valuable this cryptocurrency was, and worked feverishly to develop it to its maximum potential.