The article discusses the evolution of digital identity in the transition from Web2 to Web3, emphasizing how the emergence of Decentralized Identity (DID) returns control of identity to users and changes the way social data is used. DID features low consensus costs, composability, and global accessibility, driving the development of decentralized societies. Although DID faces challenges such as information silos, conflicts between privacy and transparency, and insufficient incentives for identity value, it still holds broad application potential in the era of on-chain behavior and has become an important component of Web3.