IoT has turned into an amazing system of worldwide and worldwide changes, including numerous internet advisors, interchanges, and information trade. This paper presents state-of-the-art background, introduction, characteristics, challenges, threats, attacks, related work, and security architecture and research limitation of IoT technology. This paper discusses key security issues and attacks over different layers of IOT along with its existing prevention techniques. This paper deals with the security of services used in IoT. In detail, IoT devices are mentioned in this paper, which are the premise of IoT and their significance. In addition, IoT Security Architecture highlights some recent studies. This paper is far from comprehensive and mainly focuses on attacks and IoT devices prevention mechanism and covers related discussion and arguments.