French window are one of the most classic types of windows. Often seen in kitchens, they are attached to the frame be one or more hinges at the side. These windows can open inwards or outwards, but it is most common for them to open into the household while having outside shutters open away from the house. Sliding windows must always have some play in them to allow the tracks to work properly. An added bonus of the casement window is that they allow the least air in, even when it is very blowy outside.