Plant volatiles (PVs) are lipophilic molecules with high vapor pressure, serving various ecological roles. The synthesis of PVs involves the removal of hydrophilic moieties and various chemical reactions such as oxidation, hydroxylation, reduction, methylation, and acylation. PV biosynthetic enzymes often produce multiple products from a single substrate or act on multiple substrates. Genes for PV biosynthesis evolve through gene duplication and divergence, leading to convergent evolution in distally related species. The number of identified PVs exceeds 1000, and their functions are not always related to volatility. Most PVs are restricted to specific lineages and are involved in species-specific ecological interactions. Improvements in analytical techniques have made PVs one of the best-studied groups of plant secondary metabolites. The largest class of PVs is derived from isoprenoid pathways, where enzymes like terpene synthases (TPSs) catalyze the formation of various terpenoid compounds. TPSs can produce one or two major products and several minor products, with the proportions influenced by specific residues in the active site. The second-largest class of PVs contains aromatic compounds, often derived from shikimate pathways. A third group of PVs is produced by oxidative cleavage and decarboxylation of fatty acids. Enzymes for PV biosynthesis often belong to large families, and some can use multiple substrates. For example, carboxyl methyltransferases and acyltransferases can produce different products depending on the available substrates. These enzymes often evolve from non-PV enzymes, and changes in a few critical residues can alter their substrate specificity. The spatial and temporal modulation of PV biosynthesis is influenced by environmental factors and often follows a rhythmic pattern. Each plant species has a unique set of volatiles, and the discovery of PV pathways and enzymes has been significant. However, many enzymes responsible for known PVs remain uncharacterized, and the internal and external factors influencing PV biosynthesis need further study. The transport, storage, and emission of these compounds are also areas that require more research.Plant volatiles (PVs) are lipophilic molecules with high vapor pressure, serving various ecological roles. The synthesis of PVs involves the removal of hydrophilic moieties and various chemical reactions such as oxidation, hydroxylation, reduction, methylation, and acylation. PV biosynthetic enzymes often produce multiple products from a single substrate or act on multiple substrates. Genes for PV biosynthesis evolve through gene duplication and divergence, leading to convergent evolution in distally related species. The number of identified PVs exceeds 1000, and their functions are not always related to volatility. Most PVs are restricted to specific lineages and are involved in species-specific ecological interactions. Improvements in analytical techniques have made PVs one of the best-studied groups of plant secondary metabolites. The largest class of PVs is derived from isoprenoid pathways, where enzymes like terpene synthases (TPSs) catalyze the formation of various terpenoid compounds. TPSs can produce one or two major products and several minor products, with the proportions influenced by specific residues in the active site. The second-largest class of PVs contains aromatic compounds, often derived from shikimate pathways. A third group of PVs is produced by oxidative cleavage and decarboxylation of fatty acids. Enzymes for PV biosynthesis often belong to large families, and some can use multiple substrates. For example, carboxyl methyltransferases and acyltransferases can produce different products depending on the available substrates. These enzymes often evolve from non-PV enzymes, and changes in a few critical residues can alter their substrate specificity. The spatial and temporal modulation of PV biosynthesis is influenced by environmental factors and often follows a rhythmic pattern. Each plant species has a unique set of volatiles, and the discovery of PV pathways and enzymes has been significant. However, many enzymes responsible for known PVs remain uncharacterized, and the internal and external factors influencing PV biosynthesis need further study. The transport, storage, and emission of these compounds are also areas that require more research.