Although the electron distribution at the Fermi surface of a metal has long been considered to be well understood, some anomalies of electronic behavior such as magnetoresistivity have hinted that this understanding was not complete. In 1968 Albert W. Overhauser (Purdue University) proposed a model of a Fermi‐surface instability that he called “charge density waves.”1However, the validity of charge density wave theory has only now been established by the experimental observation of periodic structural distortions—unique consequences of this type of instability.