Final answer:
Iphigenia was killed as a human sacrifice to appease the goddess Artemis so the Greek fleet could sail to Troy, deeply affecting her family and leading to a cycle of revenge.
Step-by-step explanation:
The ancient Greek myth of Iphigenia is a tragic tale that explores themes of sacrifice and fate. Iphigenia was killed as a human sacrifice because the Greek fleet was unable to sail to Troy due to calm winds, and it was prophesied that only her sacrifice would appease the goddess Artemis to allow their journey to continue. This act had substantial effects: it caused great sorrow for her father, Agamemnon, and the rest of her family, and later it became a catalyst for a cycle of revenge within her family, which is detailed in various Greek tragedies and mythical narratives.
The effects of Iphigenia's death were significant in Greek mythology. Her sacrifice was central to the unfolding of the events in the tale of the Trojan War, influencing the fates of many characters. Furthermore, in some versions of the myth, it's said that Iphigenia was spared by Artemis and whisked away to Tauris, where she became a priestess tasked with sacrificing foreigners, leading to a dramatic reunion with her brother, Orestes, which ultimately saved them both from their grim destinies.