The recent era has witnessed a significant orientation towards investment and simulation of the real systems into smart systems that are based on using the Internet-of-Things. Internet-of-Things aims to interconnect distributed smart devices or sensors for simulating a specific domain system. Big data is considered to be a result of this connection. This research aims at discussing the importance of Internet-of-Things and examining the risks of simulating smart systems. Furthermore, the study also examines the architecture of smart Internet-of-Things (IoT) system and a structure layer of IoT risks by depicting a structure of Internet-of-Things challenges. The structure’s design is based on four layers that include: authorization, big data, security, and integrity. This paper extracts the risk impact level (from highest to lowest) of various smart applications. The study also shows a comparison between multiple smart applications of Internet-of-Things in various domains and the main challenges that are faced by them. A comparative study of previous research studies, presented in this league, reveals that the attacks and hacks are the highest risks for smart applications. After which, data integrity is the next issue of concern while using the smart applications.