Roll, Pitch, and Yaw

Imagine three lines running through an airplane and intersecting at right angles at the airplane's center of gravity.

• Rotation around the front-to-back axis is called roll.
• Rotation around the side-to-side axis is called pitch.
• Rotation around the vertical axis is called yaw.

See http://www.nasm.si.edu/exhibitions/GAL109/NEWHTF/HTF541B.HTM