Normally the term is applied to mountainous and glacial terrain. In glaciology the term refers to areas of permanent snow cover.
Glaciers originate in snowfields. The lower end of a glacier is usually free from snow and névé in summer. In the upper end and above the upper boundary of a glacier the snow field is in fact and ice field covered with snow. The glacier upper boundary, where it emerges from a under a snow field, is ill-defined because of gradual transition.