The source code of Bitcoin stipulates that it must have a restricted and finite quantity. As a result, only 21 million Bitcoins will ever be generated. These Bitcoins are added to the Bitcoin supply at a predetermined rate of one block every ten minutes on average. The supply of Bitcoins will be depleted once miners have unlocked this number of Bitcoins. It’s possible, however, that the protocol for Bitcoin will be altered to allow for a higher supply.