Echo was an Oread in Greek mythology, a mountain nymph that lived on Mount Kithairon.
Zeus was quite attracted to nymphs and often visited them. Hera, his wife, jealous of his various affairs, followed him trying to catch him. However, Echo would engage Hera in long-winded conversations, giving the time to Zeus to evade her. At some point, Hera realised the plot of Echo and cursed her to only be able to repeat the last words that another person just said.
After being cursed, Echo came across a beautiful young man named Narcissus, but was unable to talk to him because of the curse. She simply followed him in the woods. Narcissus, having lost his companions with whom he had gone hunting, started shouting "Is anyone there?" Echo, given the opportunity, repeated the words. He shouted again "Let's come together" to which Echo rushed onto him repeating his words. However, Narcissus rejected Echo, and she was left in despair. Narcissus came across a lake and there, he fell in love with his own image, causing his death, unable to move. Echo mourned for him and eventually died away herself, leaving only her voice behind.