This paper deals with the signification of effective technologies for the people. Nowadays, IoT technology is working main role in human life. In recent years, smart home system and smart city security is one based on Internet of Things (IoT) technology, which support and facilitates to monitor the appliances to increase the availability of various gadgets for the aim of home automation with tough security. So that, the IoT has been exploit as one of the key features for the upcoming of wireless sensor network in order to be able to operate without human involvement. In this paper, the most decisive researchers related to security of smart home and smart city system based IoT field has been reviewed and discussed. Significant characteristics of this studies ranges from using platforms, applications to the uses of protocols communication among servers, users and different used tools. in this study we discussed the privacy and security of home to protect from any bad event such theft, fire or any motion happen in spite of if the owner inside or outside home. For this purpose, so many hardware and software object used by various studies.