Final answer:
An interconnect is a partnership among cable systems in a certain area for advertising purposes, allowing a broader audience reach and influencing cable advertising revenue since the 1980s.
Step-by-step explanation:
An arrangement where a group of cable systems in a geographic area are joined together for advertising purposes is known as an interconnect. This allows advertisers to reach a larger audience across the connected network of cable systems. Cable programming also enables national networks to reach local viewers directly through a local cable company hub, without depending on transmitting through airwaves which required the existence of local affiliates previously. With the emergence of cable and satellite broadcasts, specialized channels could focus on particular audience demographics, reshaping advertising strategies and revenue sources.
Historically, networks depended on local affiliates to reach viewers through the affiliates' transmission towers which had limited radii; each network required an affiliate in major cities. However, cable technology permits networks to reduce their reliance on these local affiliates by transmitting signals directly to homes through coaxial or fiber optic cables, bypassing over-the-air broadcast methods. As technology progressed and household access to cable and satellite broadcasts increased, by the mid-1980s, cable television networks began to receive a significant portion of advertising revenue, starting to compete with the major networks.