One of the major changes in the last decade in e-health has been the development of monitoring technologies for smart homes. An important part of such a monitoring system are the sensors. Sensors measure physical variables and transform this information to numerical values as input to smart algorithms. This chapter gives an overview of different types of sensors and their applications as well as new types of sensors and trends. It aims to give a nontechnical introduction in the emerging technologies of sensor design and applications. It also discusses topics which are relevant with respect to architectural choices, communication aspects, installation, and acceptance by the end user. Finally, some projects are mentioned which use sensor information in an e-health environment as illustration of the information covered in this chapter.