Evidence for redshift quantization is reviewed and summarized. The cosmic background rest frame appears to be central to the effect. Periods are consistently found to be members of a set predicted by the ninth-root Lehto-Tifft rule which has implications relating to the possible nature of time, particle physics and cosmology. Galaxies can be divided into four morphological families associated with particular classes of periods. Numerous examples are given including recent work where redshifts appear to show evidence of changes between related quantized levels.