Echo fell in love with a vain youth named Narcissus, who ignored her. Narcissus found a pool of water and stared at his lovely reflection until he died. Echo watched him until she pined away, now her voice remains, repeating the last few things people say.
The Greek version of the story of Echo (the above is of Roman origin [Ovid]) is as follows:
Echo was a very beautiful and musical nymph. She could sing and play many instruments. She lived deep in the woods and denied the love of any man or immortal. She therefore attracted the hatred and anger of many, including the god Pan whose love she turned down. Pan caused his followers the shepherds to kill Echo and tear her to pieces that were subsequently scattered far and wide. Gaia, the Earth goddess, received the pieces in her bosom and thus Echo, scattered now all over the earth, retained her voice and talents answering or imitating every sound or voice.