Bitcoin, Ethereum, and almost all cryptocurrencies out on the market today use the proof-of-work model. POW requires computers to “mine” cryptocurrency by solving complex mathematical problems aka decryption. For every problem these mining computers solve, they are rewarded with some cryptocurrency. Therefore, the cryptocurrency is the proof of their “work”. At the time this process was created, it was assumed that the computer power it takes to mine the coins would make it almost impossible to corrupt information on the blockchain due to the cost of the electricity the computers were using. This was an ingenious solution to possible attacks on the system, but as blockchain technology advanced, it became clear that the POW model was unsustainable and insufficient for the needs of the world at large.