Bitcoin's blockchain hits a unique milestone in April as the 17th millionth Bitcoin was mined.

Bitcoin is like digital gold in many ways. Like gold, bitcoin cannot simply be created arbitrarily, it requires work to "extract". Gold must be mined out of the ground, and bitcoin must be "mined" via computational means. Linked with this process is the stipulation set forth by the source code of bitcoin that, like gold, it must have a limited and finite supply. In fact, there will only ever be 21 million bitcoins ever produced, and these are introduced to the bitcoin supply at a fixed rate of one block every ten minutes, on average. Moreover, the amount of bitcoin released in each of those blocks is reduced by half on an every four year schedule.

KEY TAKEAWAYS

• There are only 21 million bitcoins that can be mined in total.
• Once bitcoin miners have unlocked all the bitcoins, the planet's supply will essentially be tapped out, unless bitcoin's protocol is changed to allow for a larger supply.
• Supporters of bitcoin say that, like gold, the fixed supply of the currency means that banks are kept in check and not allowed to arbitrarily issue fiduciary media.
• Miners will still be incentivized to validate the bitcoin blockchain because they will collect transaction fee from the users.