'Soap opera is daily serial melodrama that originated in the United States on radio and then became popular on daytime television in many countries. Soap operas received the name because soap manufacturers first sponsored them on radio. For many years, a number of critics considered soap operas, though popular, to be a low type of mass-market entertainment. However, many critics have re-evaluated soap operas, assessing them as one of the few original American art forms...'

(quote from The World Book Encyclopedia
2015 edition
Volume So-Sz
18)

During the 1960s, soap operas were on daytime TV, the same time each day from Monday through Friday. On Monday, the episode summarized and provided some closure on the previous week while opening up a new storyline. Friday episodes were 'cliffhangers', leaving the audience anxious to return to the show come Monday. 'The Guiding Light', 'As the World Turns', and 'General Hospital' and 'The Edge of Night' are four that were very popular across many years, social phenomena. Many a homebody refused to miss a single episode of their favorite soap.