What are some important facts about the Armanian Genocide?
I would say that the most important fact to know about it is that one to one and a half million people were killed in this event. No matter what else happened, these were real people who lost their lives.
Perhaps the second most important thing to know is that this is an intensely political topic, especially for the Turks. Turkey (the massacres were committed by Turks back in the days of the Ottoman Empire -- WWI to be specific) are very adamant that this was not a genocide. They argue that the number of Armenians that died is overstated and they say that Turks were killed by the Armenians as well. They argue that this makes the episode merely a part of more "normal" conflict, not a genocide.
In addition to the information already provided, I would say that there are two specific facts that are highly relevant to the study of the Armenian Genocide. The first would be that the Turkish government refuses to acknowledge its role in the genocide. To the Turkish government, the loss of life was unfortunate, but not one entirely attributable to the Turks. Additionally, I would say that another fact would be that the chaos of the world setting during World War I helped to conceal the actions of the Turkish government. This fact could not be overlooked in discussing the Armenian Genocide because it is so important in the narrative of the history of such a terrible moment.