The story goes that a customer at a small restaurant in rural Quebec asked the chef to put some cheese curds on top of his chips. The chef supposedly said 'ça va faire une maudite poutine' - which roughly means 'that's going to make a right mess'. The name stuck.
Cheese curds are the key. They are little fresh lumps of cheese that haven't been pressed into a block yet. When they are very fresh, they squeak when you bite them - that is the sign of really good poutine. The gravy has to be hot enough to soften them but not melt them away.
Real Quebec poutine is simple: chips, curds, gravy. Nothing else. But across Canada there are now hundreds of versions - with pulled chicken, with bacon, with peas, with mushrooms, even with maple syrup. Some restaurants serve only poutine, with dozens of different toppings.
Poutine has spread far beyond Quebec. In Canada, you can find it at hockey arenas, in airports, even at the parliament canteen in Ottawa. November in Montreal hosts an annual poutine festival where chefs from across the country compete to make the best version.