**Abstract**

Biosensors are remarkable devices that convert biological reactions to chemical compounds into measurable signals, allowing for specific detection of target analytes. The classification of biosensors is based on the type of bioreceptor or transducer used. They have diverse applications in environmental monitoring, detection of toxins, pharmaceuticals, prosthetics, biotechnology, and biomedical engineering, with a crucial role in monitoring soil, water, and food quality. In the field of health and biomedicine, biosensors have undergone significant advancements in diagnosis and treatment of diseases by providing highly accurate results. This chapter focuses on the advancements and applications of biosensors in various biotechnological domains.

**Keywords:** biosensor, measurable signal, specific detection, target analyte, bioreceptor, wearable biosensor
