1. What is the Island?

What is its purpose? How is it masked from the real world? Who is Jacob in relation to the island? What is the mysterious black monster that lives upon it, and why do corpses regularly show up as illusions? There is something about the island that specifically draws all of these strange phenomena, and therefore it needs to be the first thing we have to understand. Is it sentient? Who settled there first, the Others or the Dharma initiative? This is a special place, which has been referenced many times in the show, with healing abilities and mysterious occurrences that are unique. Where is this island, and what exactly is it? Why do all the pregnant women die?