A bitcoin halving is imminent. Here's what that means.

Bitcoin is expected to go through a "halving" within the next day or two, a preprogrammed event that could impact production of the world's largest cryptocurrency. 

A halving, which occurs about every four years, was designed by bitcoin's creator, Satoshi Nakamoto, to effectively reduce by half the reward that miners of the digital token receive approximately every four years, or whenever a certain number of blocks are added to the blockchain. The idea is that by cutting in half the amount of bitcoin miners currently receive for their efforts, fewer bitcoins will enter the market, creating more scarcity of the cryptocurrency.

That's sparked some speculation that the halving could cause a surge in demand and push up the price of bitcoin, which has already risen almost 50% since year start. Much of the credit for bitcoin's recent rally is given to the early success of a new way to invest in the asset — spot bitcoin ETFs, which were only approved by U.S. regulators in January.