Cryptocurrencies such as bitcoin, dogecoin and ethereum are akin to digital gold, and the algorithm that generates a cryptocurrency is available for download on developer websites and, in theory, available for anyone to use to create new cryptocurrency. But the process is highly competitive because the actual amount of cryptocurrency to be put in circulation is limited. These limits vary depending on the cryptocurrency and are set by whoever created the code. For instance, the bitcoin algorithm limits the number of bitcoin that can be generated to 21 million. At that point, no more will be made.