Web3 security has become a defining concern as decentralized finance, NFTs, and smart contracts gain mainstream traction. Unlike traditional systems, blockchain transactions are irreversible, making exploits particularly damaging. Common risks include smart contract vulnerabilities, phishing attacks, private key mismanagement, and protocol-level flaws. High-profile hacks have exposed weaknesses in auditing practices and overreliance on unaudited code. While tools like multi-signature wallets and hardware storage improve safety, user awareness remains a critical weak point. Developers must adopt rigorous testing, formal verification, and continuous monitoring. At the same time, regulators are beginning to push for clearer standards, which may enhance trust but challenge decentralization principles. Ultimately, Web3 security requires a shared responsibility model between developers, platforms, and users.