The article reviews the structure and function of coronavirus spike proteins, which are crucial for viral entry into host cells. The spike protein consists of two subunits, S1 and S2, with distinct roles. S1 binds to host receptors, while S2 facilitates membrane fusion. The article discusses how different coronavirus strains recognize various host receptors through their S1 domains and how the spike proteins undergo conformational changes to facilitate membrane fusion. It also explores the evolutionary origins and mechanisms of receptor recognition and membrane fusion, highlighting the complex evolutionary relationships among these proteins. The review emphasizes the importance of understanding these mechanisms for controlling the spread of coronaviruses and preventing future outbreaks.The article reviews the structure and function of coronavirus spike proteins, which are crucial for viral entry into host cells. The spike protein consists of two subunits, S1 and S2, with distinct roles. S1 binds to host receptors, while S2 facilitates membrane fusion. The article discusses how different coronavirus strains recognize various host receptors through their S1 domains and how the spike proteins undergo conformational changes to facilitate membrane fusion. It also explores the evolutionary origins and mechanisms of receptor recognition and membrane fusion, highlighting the complex evolutionary relationships among these proteins. The review emphasizes the importance of understanding these mechanisms for controlling the spread of coronaviruses and preventing future outbreaks.