Recent research in authentication for Vehicular Ad Hoc Networks (VANETs) focuses on developing secure, lightweight, and privacy-preserving mechanisms to verify vehicle identities while ensuring fast communication in highly dynamic environments. Traditional public key infrastructures are being enhanced with certificateless and group-based authentication schemes to reduce computational overhead and eliminate certificate management complexity. Blockchain and fog-assisted frameworks are increasingly employed to achieve decentralized trust management, traceability, and tamper resistance. Researchers are also exploring physical unclonable functions (PUF)-based and cross-layer authentication methods that exploit wireless channel features for added resilience against spoofing and replay attacks. Furthermore, conditional privacy-preserving protocols enable anonymous message exchange while allowing authorized authorities to trace misbehaving vehicles when needed. These innovations collectively strengthen trust, scalability, and security, forming the backbone of reliable communication in next-generation intelligent transportation systems.