Electronic nose devices have got attention in the field of sensor technology during the past twenty years, largely because of the discovery of various applications derived from research in diverse fields of applied sciences. Recent applications of electronic nose technologies have come through advances in sensor design, material improvements, software innovations and progress in microcircuitry design and systems integration. The study of many newe-nose sensor types and arrays which arebased on different detection principles and mechanism, is closely correlated with the expansion of new applications. Electronic noses have provided a plethora of benefits to a variety of commercial industries, including the agricultural, biomedical, cosmetics, environmental, food, processing, pharmaceutical, military, regulatory, and various scientific research arenas. Advances have improved product attributes, uniformity and consistency as a result of increases in quality control abilities afforded by electronic-nose auditing of all phases of industrial manufacturing processes. This paper is a review of the major electronic-nose technologies, developed since this specialized area was born and became prominent in the mid 1980s, and a depiction of some of the more important and useful applications that have been of greatest profit to human.