Marshall McLuhan's hot and cool categories

The electric media of television and computers, argued McLuhan, would liberate us from our dependence on the printed word. Print was what he called a “hot” medium, one that absorbed all of our attention and left little room for participation. The medium it had supplanted, the spoken word, was by contrast a “cool” medium that left plenty of space for participation.

Reading, to put it simply, is a lonely pursuit, while speech is a social one. So when we became readers, rather than listeners, we sacrificed our shared, tribal consciousness and became locked into private consciousness. Printed text, in McLuhan’s view, led to everything from the rise of individualism to the specialization of jobs in factories.