The drift velocity is a charge carrier population's mean velocity relative to its material's rest frame. It describes the net transport superposed on microscopic motion. For a single species, current density is ; for electrons, reverses the direction. It is distinct from the propagation speed of an electrical disturbance. [ref]
https://openstax.org/books/university-physics-volume-2/pages/9-2-model-of-conduction-in-metals. Ling, Sanny and Moebs, §9.2: drift and transport
.The mean velocity of the electron population associated with a net electric current, distinct from random thermal or Fermi motion. Its sign is opposite to conventional current for negative charge carriers. Its usually small magnitude is not the propagation speed of an electromagnetic signal in a transmission line.
For sinusoidal current density and constant carrier density , the electron drift velocity is . Its displacement has amplitude and zero net change over a full cycle. The distance accumulated by this drift alone in one cycle is . With an RMS current, . This does not measure the much larger microscopic path due to Fermi velocity and electron-phonon scattering.
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Drift velocity refers to the average velocity that charged particles, such as electrons, attain due to an electric field in a conductor. When an electric field is applied across a conductor, it causes the free electrons (or charge carriers) to move in a specific direction. However, these electrons are also subject to random thermal motion, which causes them to collide with atoms in the material.