The term "party line" refers to a telephone service where multiple phone subscribers share a single wire and listen in on each other's conversations. This was common before the advent of direct distance dialing, when long-distance calls were made through an operator who would connect the caller with another party by establishing a connection between their two phones. Since only one line connected all subscribers, they could eavesdrop on others' conversations if they picked up their phone while someone else was using it. This led to the phrase "party lines" being used to describe any situation where people share access or resources and must cooperate in order for everyone to benefit.