How Does “Proof-of-Work” Secure a Blockchain?
Proof-of-Work (PoW) secures a blockchain by requiring miners to expend significant computational effort (hash power) to solve a complex mathematical problem to create a new block. This effort makes it prohibitively expensive and energy-intensive for a malicious actor to gain control of the network (the 51% attack).
The longest chain of blocks is accepted as the valid history.
