The Internet of things (IoT) has recently become an important research topic because it integrates various sensors and objects to communicate directly with one another without human intervention. The IoT is proposed to improve the quality of human life by automating some of the basic tasks that humans must perform. In that sense, monitoring and decision making can be moved from the human side to the machine side. One of the main applications of IoT in healthcare is in assisted living scenarios. Sensors can be placed on health monitoring equipment used by patients. The information collected by these sensors is made available on the Internet to doctors, family members and other interested parties in order to improve treatment and responsiveness. The IoT has the potential to give rise to many medical applications such as remote health monitoring, chronic diseases, and elderly care. This paper presents an overview of IoT and its Applications in Healthcare and security challenges in the IoT