Abstract: Sensor networks offer a powerful combination of distributed sensing, computing and communication. They lend themselves to countless applications and, at the same time, offer numerous challenges. Energy is the scarcest resource of WSN nodes, and it determines the lifetime of WSNs. WSNs may be deployed in large numbers in various environments, including remote and hostile regions, where ad hoc communications are a key component. Wireless Sensor Networks provide capabilities that are valuable for continuous, remote monitoring for healthcare applications; they can be deployed inexpensively in existing structures without additional IT infrastructure. This paper presents an overview of the different applications of the wireless sensor networks and various Challenges. Energy management is an important parameter in increasing the network lifetime and thereby meeting user requirements to perform various applications in different fields.

Keywords: WSN Applications, Challenges, Classification.