Green leaf volatiles (GLVs) are the metabolites obtained from polyunsaturated fatty acids, playing crucial roles in biotic stress responses and ecological interactions. These compounds include six-carbon (C6) saturated and unsaturated aldehydes, alcohols and keto compounds derived from linoleic acid (C18:2n6) and α-linolenic acid (C18:3n3). These compounds are produced through lipoxygenase-mediated hydroperoxygenation of the fatty acids and their cleavage by hydroperoxide lyase. The generation of C6 volatiles is triggered by damage from pathogens or herbivores at the affected site. GLVs serve as a direct defence mechanism against microbes and fungal pathogens, and also provide systemic defence by upregulating defence-related genes at distal, undamaged sites. Additionally, GLVs mediate indirect defence responses through complex ecological interactions. Volatiles emitted by a damaged plant can signal neighbouring plants to initiate pre-defence mechanisms, known as plant-talk or eavesdropping. Herbivore-induced volatiles also facilitate indirect defence through tri-trophic interactions by attracting natural enemies of herbivores, thereby minimizing herbivore-induced damage. This review aims to highlight the production of GLVs and their physiological and ecological significance.