The Internet of Things (IoT) which is dynamic, intelligent, and ubiquitous. Academic and commercial organizations mostly prefer the Internet of Things for research. Day by day, IoT publicity is increasing. An intelligent network that concatenates all things (IP or non-IP based) to the Internet for information interchange and communication is the Internet of Things (IoT). This paper provides the IoT system with its applications, challenges, and open issues and discusses the state-of-the-art methods of the IoT system and its layered architecture. Sensors and actuators are combined in the IoT system for new services and products with highly efficient, low costs, and user friendly. The IoT is ordinarily composed of various advanced technologies like software, actuators, sensors, and electronics because of Micro-Electro-Mechanical Systems (MEMS) comprising electronic and mechanical components at
the micron level.