According to Wikipedia, in 1982 Carnegie Mellon University of Pittsburgh installed a Coke machine in one of its buildings. Not just any Coke machine, of course, but a modified one that became the first appliance ever connected to the Internet, such as it was at that time. From this connection one could remotely monitor the vending machine’s inventory and the temperature of the drinks it held.
During the next decade and more, the concept and usefulness of connecting things to the Internet gained the attention of researchers, developers and, finally, the business community. As the concept of connecting to the Internet took hold, so too did the concept of connecting things to each other.