Numerous materials have been deposited as amorphousfilms but our understanding of this phase is lacking. Since opinions regarding short-range order diverge, the similarities and differences between the liquid and amorphous phases are discussed first. It is then concluded from experimental data that the atomic arrangement in “ordered agglomerates with spherical close packing” differs from that in small crystallites. A review of experimental results for alloys, for elements with homopolar binding, and for semimetals and metals indicates that the metastable disorder in these groups of materials displays different characteristics. Interpretations for the varying degree of thermal stability, for size-dependent transitions, and for the kinetics of the transformation are given. Based on these considerations, a concept for the formation and crystallization of amorphousfilms is developed which shows the progressive change of the characteristics among the groups of materials.