What Is the Primary Role of Proof-of-Work (PoW) in Securing the Bitcoin Network?

PoW's primary role is to prevent double-spending and ensure consensus across the decentralized network. It requires miners to expend computational energy to find a valid block hash, making it economically infeasible for a malicious actor to rewrite the transaction history.

This high cost of attack secures the ledger and incentivizes honest participation.