“8/7c” or “8 – 7 Central” means that this show is occurring at 8 o’clock Eastern Time, or 7 o’clock Central time. The reason Eastern Time is commonly omitted and “Central Time” / “c” is not is because most of the American population and much of American media apparatus is concentrated on the coasts of the country, mostly the East Coast actually, and thus Easterners are considered the “default”; that means shows first air for Eastern viewers, and they are also the demographic advertisers and television networks first accommodate for scheduling before other time zones. (Show performance at 8 – 11 PM is a hugely important metric for advertisers and the continued viability of network television shows; that time block is commonly known in the United States as prime time).

Eastern Time viewing and Central Time viewing are often scheduled together in network television programs, because simultaneity for them is not too unaccomodating. Mountain Time and Pacific viewers can and often are scheduled for their own separate block.