Wireless sensor network encompasses the characteristics of authentication, privacy, integrity, non-repudiation, and anti-play back. The greater the dependency of information sent or received in the network, the greater the security risks. Various security issues have been considered in ad hoc networks but these are not applicable to WSN because of the disparity in the architecture of the two networks. Also, quite a number of other security schemes are already being proposed. If the cluster formation design currently being investigated, is to be effective in saving energy, there is need to look at the security between the individual nodes, neighbouring nodes and the base station. Earlier, it was mentioned that there are numerous constraints affecting the performance of a wireless sensor network. Additional restraints includes, low memory and low energy resources. Attacks on network availability also arise when considering that wireless sensor networks (WSN) are more vulnerable to denial-of-service (DOS) attacks and algorithmic complexity attack as shown. They are vulnerable mainly due to the location of the sensor nodes and limitation of the sensor coverage. The video shows further application of WSN.