Tilt and turn windows have gradually made their way from Europe over to the United States. These windows are similar to casement windows in that you can open the panes so they swing out from the frame, but they also give you the option of tilting the tops of the windows open by a few inches. You can tilt them toward the exterior or interior of your house depending on the style of window. You can choose which style, however, so you need to figure out which tilt direction is best for you.
These windows tilt open at the top in order to allow better airflow. While you could still get air if the windows opened at the bottom, the opening at the top allows cool air, which tends to sink, to flow right into your house. When the window is open at the bottom, you need stronger breezes to push more into your house.
However, the open top presents issues with rain. You can't keep these windows tilted open in heavy rain or in storms where the wind is so strong that the rain is nearly horizontal. However, you can keep them open in lighter storms.
A window that tilts out, toward the porch or yard, may still allow some water to drip in unless the window is protected by an overhang. Water can end up dripping onto the interior side of the open pane and then trickling down inside to the room. Windows that tilt in toward the room won't have that problem, but you do risk rain getting in if the wind changes direction.
Windows that tilt outward are like casement windows in that the hardware isn't accessible to someone outside unless the pane is fully open. It is hard for someone outside to get in if the window is only tilted open at the top. For windows that tilt inward at the top, however, it could be easier for someone to try to push the pane inside further or access the hardware. That depends on how far the window tilts open.
Watch Your Head
Finally, if you have large window panes tilted inward toward a room, you have obstacles for people's heads. Be sure to place furniture like seats well away from the windows so that anyone standing up won't risk hitting their heads on the panes, and anyone trying to walk behind the seats won't have to duck.
European windows are versatile and they look very trim and clean. Go see some at a window dealer to get a better idea of how far they open, because added ventilation can make your house feel very comfortable in summer.