Early television unquestionably evolved from the network organization of radio.
Television certainly began as a network-organized medium . . . . By the early 1960s, network-era conventions were more fully in operation: the television set (and for some, an antenna) provided the extent of necessary technology; competition was primarily limited to programming supplied to local affiliates by three national networks that dictated production terms with studios; the networks offered the only outlets for high-budget original programming; thirty-second advertisements—the majority of which were sold in packages before the beginning of the season—supplied the dominant form of economic support and were premised upon rudimentary information about audience size; and audiences, which exercised no control over when they could view particular programs, chose among few, undifferentiated programming options.
U.S. “television” meant the networks ABC, CBS, and NBC.

. . . . These networks were organized hierarchically with many layers of managers, and each was administered by a figurehead with whom the identity and vision of the network could be identified.

. . . . The networks forced producers to shoulder significant risk while offering limited reward through a system in which the producers financed the complete cost of production and received license fees (payments from the networks) often 20 percent less than costs.
Single-sponsoring to multi-sponsoring program
Television was predominantly

• a non-portable,
  
• domestic medium,
  
• with most homes owning just one set.