The closer to red cool colors get on the wheel, the warmer they become. The last stop on the cool side of the wheel is violet-red. After violet-red, colors start to advance again.
Color theory provides a general framework to describe the behaviors of colors, and exceptions to these generalizations abound. Still, the tendencies of warm colors to advance and cool colors to recede are almost always true.
If you have a room with a low ceiling and you want the room to feel taller, paint the ceiling a white that's been tinted with blue. Similarly, if you have a very wide room that you want to feel closer and more intimate, then paint the room in a warm color and it will do just that.
How would you use warm and cool colors in your own home?
More: Choosing Hues: Roll with the Color Wheel