Essential oil production in plants is a complex process regulated by physiological and developmental factors. Essential oils are secondary metabolites that are highly integrated with the plant's overall physiology, depending on the metabolic state and developmental program of the tissue producing them. These oils are ecophysiologically and environmentally friendly, and their production is influenced by various factors, including environmental conditions and genetic traits. The review discusses the current understanding of the biosynthetic mechanisms involved in essential oil production, highlighting the importance of these oils in various industries, including perfumery, cosmetics, and pharmaceuticals. Essential oil-producing plants are not restricted to any specific taxonomic group and are found across the plant kingdom. They include both dicots and monocots in various habitats, covering a wide range of families. The diversity of essential oil plants is reflected in the variety of epidermal structures that produce or store these oils, as well as the wide range of chemical compositions of the oils. The biogenetic pathways for essential oils may have evolved early in the history of land plants, with recent discoveries indicating that some essential oil terpenoids are synthesized through a bacterial-type metabolic pathway in the plastids of glandular trichomes. Terpenoids are a major component of essential oils, but many oils also contain phenylpropanoids. Essential oils are highly complex, containing a variety of chemically distinct compounds. While major components are typically used for chemotaxonomic identification, minor components can also have significant organoleptic roles. The review also highlights the importance of essential oils in global trade and the need for research to improve oil yields and cultivation economics under diverse conditions. Major essential oil-producing plants and their key constituents are listed, along with the methods used for oil extraction and trade practices.Essential oil production in plants is a complex process regulated by physiological and developmental factors. Essential oils are secondary metabolites that are highly integrated with the plant's overall physiology, depending on the metabolic state and developmental program of the tissue producing them. These oils are ecophysiologically and environmentally friendly, and their production is influenced by various factors, including environmental conditions and genetic traits. The review discusses the current understanding of the biosynthetic mechanisms involved in essential oil production, highlighting the importance of these oils in various industries, including perfumery, cosmetics, and pharmaceuticals. Essential oil-producing plants are not restricted to any specific taxonomic group and are found across the plant kingdom. They include both dicots and monocots in various habitats, covering a wide range of families. The diversity of essential oil plants is reflected in the variety of epidermal structures that produce or store these oils, as well as the wide range of chemical compositions of the oils. The biogenetic pathways for essential oils may have evolved early in the history of land plants, with recent discoveries indicating that some essential oil terpenoids are synthesized through a bacterial-type metabolic pathway in the plastids of glandular trichomes. Terpenoids are a major component of essential oils, but many oils also contain phenylpropanoids. Essential oils are highly complex, containing a variety of chemically distinct compounds. While major components are typically used for chemotaxonomic identification, minor components can also have significant organoleptic roles. The review also highlights the importance of essential oils in global trade and the need for research to improve oil yields and cultivation economics under diverse conditions. Major essential oil-producing plants and their key constituents are listed, along with the methods used for oil extraction and trade practices.