The three-tier structure of the Internet of Things (IoT) comprises of three layers namely, the perception layer, the network layer, and the application layer. Each of these layers plays a unique role, equipped with specific devices, and facing discrete security issues. The perception layer, or the sensing layer, is responsible for collection of data from its surroundings using varied types of sensors, actuators, and RFID tags. The network layer, also known as the communication layer, is responsible for continuous data transfer between devices, servers, and gateways, utilizing a range of communication protocols. The top layer, the application layer, manages and handles the collected data, presenting user interfaces, software and algorithms for innumerous IoT uses. This paper delves into the working, devices, and security features of each layer, emphasizing the importance of security to the overall IoT framework. This paper also discusses security must-haves, such as privacy, confidentiality, authentication, access control, trust management, and compliance with rules and standards. When these security requirements are not met, it can obstruct the full realization of IoT’s transformative potential. Addressing the current research gaps in IoT security requires the development of innovative solutions in identification, wireless technology, software, and hardware, including device standards, key management frameworks, identity configuration methods, and trust management systems.