Authentication is a fundamental component of web security, enabling users to safely access online websites. The Authentication is one of the major elements of web security that facilitates users to secure access to internet websites. Traditional methods of authentication are based on password entry, multi-factor authentication (MFA), and single sign-on (SSO). Even though the methods are often followed in these times, the methods are never foolproof Passwords can be hijacked, MFA can be circumvented, and SSO depends on centralized infrastructure that can be compromised. Millions of user accounts have been exposed due to data breaches and phishing attacks, and there is a growing demand for a safer alternative. This paper discusses ways blockchain technology improves authentication in web portals. Blockchain provides decentralization, immutability, and cryptographic security that makes it difficult for hackers to steal credentials or tamper with login systems. We present why decentralized identity (DID), smart contracts, and Web3 authentication are preferable to conventional alternatives. Besides, the real-world applications and case studies will be examined to demonstrate how blockchain technology can build a more secure and user-managed authentication system. This paper aims to offer a clear picture of how blockchain technology can enhance authentication, minimize hacking threats, and build a safer online environment.