What technological innovation made client server possible?

The technological innovation that made client-server architecture possible was the development of networking protocols, particularly TCP/IP (Transmission Control Protocol/internet Protocol). This allowed different computers to communicate over a network, enabling one to act as a server providing resources and services, while others functioned as clients accessing those services. Additionally, advancements in hardware and software, such as more powerful servers and the emergence of relational databases, further facilitated this model.