Digital twin (DT) is a technique that digitally represents physical entities and has gained significant interest. It allows the replication of operations, analysis of conditions, prediction of behavior, and optimization of control. Human digital twin (HDT) extends this concept to represent individual human bodies, encompassing molecular, physiological, emotional, psychological, and lifestyle aspects. HDT shows promise in personalized healthcare (PH), enabling remote monitoring, diagnosis, prescription, surgery, and rehabilitation. However, implementing HDT poses research challenges. This survey focuses on HDT’s networking architecture and key technologies in PH applications, discussing its differences from conventional DTs, outlining its framework and functions, analyzing design requirements and challenges, presenting the networking architecture, and exploring future research directions.