Whenever a block is produced within Bitcoin´s coin issuance, miners are rewarded a certain amount of bitcoins. In the beginning, 50 Bitcoins per block were given to miners. Given that the bitcoin´s supply is fixed, set at 21,000,000 bitcoins as the maximum one, every 210,000 blocks or what is the same approximately 4 years, the block reward halves.

Halving dates:

• 1st halving: 29th November 2012
• 2nd halving: 10th July 2016
• 3rd halving: 18th May 2020

As can be seen historically every halving has triggered a bull run. Between every halving, there has been a five-phase pattern