Mining is the term used to describe the process of extracting cryptocurrency tokens from a blockchain network. This involves having computers continuously run a hashing algorithm, which takes an arbitrarily large amount of information and condenses it to a string of letters and numbers of a fixed length. The hashing algorithm hashes metadata from the most recent block using something called a nonce: a binary number that produces a unique hash value. For each new block in the blockchain, the network sets a target hash value and all the miners on the network try to guess the nonce that will result in that value.
See what it would look like with this mining simulator
The first Bitcoin miner was Satoshi Nakamoto. In 2009 he mined the first block, block 0, and earned 50 coins. By 2011 it started to enter main stream conversations and by 2014 large online retailers started to accept it. Today it is becoming the next step in online secure transactions.
There are several different coins that can be mined. We mostly talk about BitCoin as it was the first and most well known. There are currently over 1500 coins to choose from.