Understanding 51% Attacks is crucial for blockchain security. When an attacker gains majority control, they can reverse confirmed transactions, disrupting trust and economic stability. Networks with lower hash rates are more susceptible to these attacks, making decentralization and strong security measures essential. Preventing such attacks ensures the reliability of decentralized systems. Developers continually enhance blockchain security by implementing alternative consensus mechanisms like Proof of Stake (PoS) and hybrid models to mitigate these threats.