Why are people going gluten-free?

Out of all the diet fads that I have heard of, this one confuses me the most. WHY are people cutting out gluten? Do they think it will make them lose weight? Do they think that it's hindering their health in some way if they eat it? Does everyone suddenly have celiac? Do people just hear about others who have gluten intolerances, and then convince themselves that they have an intolerance? What the hell is it??