The plant hormone ethylene plays a prominent role among several intrinsic and extrinsic factors that control growth and physiology of plants. Its biological activity was discovered over a century ago. However, extensive studies on its mode of action came later. To date, it is well documented that ethylene is a versatile signaling molecule that plays an important role in many physiological processes - like growth, senescence, fruit ripening, stress responses, symbioses, and photosynthesis. Molecular-genetic analyses have revealed mechanisms responsible for ethylene production, perception, and signal transduction. The present work brings into focus the recent developments on the biochemical, physiological, and molecular basis for ethylene action in plants.