<b>A Brief Study on IoT Applications</b> The Internet of Things IoT is viewed as an ecosystem that includes smart objects with sensors, networks, and processing technologies that integrate and work together to provide an environment that provides smart services to end users. IoT brings many benefits to human life through an environment where smart services are provided to use any activity anytime and anywhere. All of these facilities and services are communicated through various applications running in the IoT environment. The most important utility achieved by IoT applications is monitoring and, consequently, rapid decision making for e cliient management. In this paper, we will explore the diversity IoT application domain to understand the various approaches of IoT applications that have recently been proposed based on the systematic literature review SLR method. The purpose of this paper is to analyze and statistically categorize and analyze current research approaches on IoT application approaches published between 2011 and 2018. According to the content of the current study selected, this study will use SLR processes that include general aspects of healthcare, environmental monitoring, smart cities, commercial and industrial testing, and IoT applications. IoT applications are compared to each other according to several technical characteristics, such as quality of service QoS , proposed case studies, and evaluation environments. It describes the results and shortcomings of each study, addresses those weaknesses, and provides tips for highlighting future research and open issues in IoT applications. Smart city applications, Cyber Security, Health care applications 23-27 Issue-2 Volume-4 N. Sathiyanathan | Selvakumar. S | P. Selvaprasanth