A pseudo force, also known as a fictitious force, inertial force, or d’Alembert force, is an apparent force that acts on all masses whose motion is described using a non-inertial frame of reference, such as a rotating reference frame. It is an imaginary force that arises when a frame of reference is accelerating compared to a non-accelerating frame. Pseudo forces do not arise from any physical interaction between two objects, but rather from the acceleration of the non-inertial reference frame itself. They are called fictitious because they are not real forces, but rather a mathematical construct used to explain the motion of objects in non-inertial frames of reference. Examples of pseudo forces include the Coriolis force, centrifugal force, and Euler force. Pseudo forces are important in physics because they help explain why objects do not follow Newtons second law of motion and "float freely" as if weightless when observed from a non-inertial frame of reference.