Biosensors are analytical devices that convert biological responses into electrical signals. They are highly specific, independent of physical parameters like pH and temperature, and are reusable. This review discusses various types of biosensors, including enzyme-based, tissue-based, immunosensors, DNA biosensors, thermal, and piezoelectric biosensors, highlighting their applications in multiple fields. Biosensors are used in the food industry for quality control, in fermentation processes for monitoring glucose levels, and in medical science for early detection of diseases such as heart conditions and cancer. They are also employed in plant biology to study metabolic processes and in defense and clinical sectors. Fluorescent biosensors are crucial in drug discovery and cancer detection. Biosensors offer advantages over traditional methods in terms of sensitivity, speed, and cost-effectiveness. They are used for detecting pathogens, toxins, and pollutants, and for monitoring metabolic processes in living cells. In medical applications, biosensors are used for diagnosing infectious diseases and monitoring cardiac markers. Future developments in biosensors include the use of nanomaterials to enhance sensitivity and functionality, and the integration of biosensors with advanced technologies for real-time monitoring and improved diagnostic capabilities. The review emphasizes the importance of biosensors in various applications and their potential for future advancements in healthcare, environmental monitoring, and biotechnology.Biosensors are analytical devices that convert biological responses into electrical signals. They are highly specific, independent of physical parameters like pH and temperature, and are reusable. This review discusses various types of biosensors, including enzyme-based, tissue-based, immunosensors, DNA biosensors, thermal, and piezoelectric biosensors, highlighting their applications in multiple fields. Biosensors are used in the food industry for quality control, in fermentation processes for monitoring glucose levels, and in medical science for early detection of diseases such as heart conditions and cancer. They are also employed in plant biology to study metabolic processes and in defense and clinical sectors. Fluorescent biosensors are crucial in drug discovery and cancer detection. Biosensors offer advantages over traditional methods in terms of sensitivity, speed, and cost-effectiveness. They are used for detecting pathogens, toxins, and pollutants, and for monitoring metabolic processes in living cells. In medical applications, biosensors are used for diagnosing infectious diseases and monitoring cardiac markers. Future developments in biosensors include the use of nanomaterials to enhance sensitivity and functionality, and the integration of biosensors with advanced technologies for real-time monitoring and improved diagnostic capabilities. The review emphasizes the importance of biosensors in various applications and their potential for future advancements in healthcare, environmental monitoring, and biotechnology.