# The three pillars of PoW
## Asymmetry
Easy to verify, hard to compute
## Puzzle/Challenge
Have to solve a very challenging(computationally) problem
## Nonce
A value used to vary inputs until the puzzle solution meets a requirement.

# Common Puzzles/Challenges for PoW
+ Bitcoin's SHA256:
Find a nonce such that ```hash(block + nonce)``` starts with a specific number of zeros.
This is usually only used for blockchains, hence there is the block. However, this could be used for other applications as well.

+ ProgPoW:
Heavily GPU and CPU intensive, as it creates a psuedo-random program that does several seemingly random operations using the nonce to generate a number that one can "mine" in order to get.

+ RandomX (Used by Monero)
Is heavily CPU-dependent, as it doesn't translate onto the GPU that well, and it works by using Just-In-Time(JIT) to create another psuedo-random program that can be mined as well. However, this uses all kinds of operations, like floating point, AES, and memory loads.