Frequent, random movements caused by the randomly spaced impacts of sub microscopic particles (atoms, molecules, or elementary particles) in the fluid surrounding a more massive and visible body. The motion is most noticeable when the body a small, suspended particle such as a mote of dust in the air. Brownian motion is a particular case of the motion called random walk. It is one factor limiting the accuracy achievable with some kinds of measuring instrument such as accelerometers. It should not be confused with the motion caused by random motions of the molecules in the body itself.