The paper provides a comprehensive review of electronic-nose (e-nose) technologies and their applications. E-noses, which mimic the mammalian olfactory system, have gained significant attention due to their ability to detect and characterize volatile organic compounds (VOCs) in various fields such as agriculture, biomedicine, cosmetics, and environmental monitoring. The development of e-noses has been driven by advancements in sensor design, material science, software, and microcircuitry. These devices consist of multisensor arrays, information-processing units, and reference libraries, enabling them to identify and classify complex mixtures of VOCs without the need for individual chemical identification. The paper highlights the importance of aroma in human society and commerce, emphasizing how e-noses can enhance product quality and consistency. It also discusses the biological olfaction process and the challenges of human olfactory sensitivity. The conceptual development of e-noses, including the evolution of sensor types such as metal-oxide, conducting polymer, and acoustic wave sensors, is detailed. The paper concludes with a discussion on the instrumentation of e-noses, their market presence, and the challenges in standardizing their nomenclature.The paper provides a comprehensive review of electronic-nose (e-nose) technologies and their applications. E-noses, which mimic the mammalian olfactory system, have gained significant attention due to their ability to detect and characterize volatile organic compounds (VOCs) in various fields such as agriculture, biomedicine, cosmetics, and environmental monitoring. The development of e-noses has been driven by advancements in sensor design, material science, software, and microcircuitry. These devices consist of multisensor arrays, information-processing units, and reference libraries, enabling them to identify and classify complex mixtures of VOCs without the need for individual chemical identification. The paper highlights the importance of aroma in human society and commerce, emphasizing how e-noses can enhance product quality and consistency. It also discusses the biological olfaction process and the challenges of human olfactory sensitivity. The conceptual development of e-noses, including the evolution of sensor types such as metal-oxide, conducting polymer, and acoustic wave sensors, is detailed. The paper concludes with a discussion on the instrumentation of e-noses, their market presence, and the challenges in standardizing their nomenclature.