This book presents a comprehensive overview of magnetic biosensor modelling and simulation. The applied model's strengths and weaknesses are highlighted and the used competencies of different modelling software, including commercial (i.e. Multiphysics modelling software) and home-made, are discussed. The sensor materials section not only explores promising materials whose properties have been utilised for sensing action but also predicts future smart materials that has the potential for sensing application. The classification section categorizes sensors into different sub-types and describes their working, focusing on prominent applications to show the benefits and drawbacks of relevant designs. The application section includes a state-of-the art update of developments in the field of each sensor type and concludes with challenges in relevant fields of research.