The Internet of Things, or IoT, has become a paradigm shift that unites the digital and physical worlds to create a world that is always linked. In order to fully realize the promise of the IoT, this article explores the fundamental technologies, protocols, and applications. We start by looking at the core technologies of the IoT, such as enhanced sensor technologies, low-power wide-area networks (LPWAN), and edge computing. We next go through the most recent protocols that guarantee effective, safe, and scalable IoT implementations, stressing the significance of standardization and interoperability. across addition, we showcase a variety of cutting-edge uses across a variety of industries, including smart cities, healthcare, agriculture, and industrial automation, to demonstrate the revolutionary potential of IoT. We hope that this thorough analysis will provide scholars, industry professionals, and decision-makers with a full knowledge of the state-of-the-art in IoT today, as well as the many potentials and challenges it brings for a connected future.