The Internet of Things (IoT) is a new paradigm which is transforming everything from the consumer market, that is, household devices to industrial applications at large scales. IoT devices and related technologies have gotten a little cheaper and broadly accepted globally. The use of proper authentication mechanisms is one way to ensure security against various attacks and maintain the availability and integrity of data and services at all times for authorized users. The most serious threat IoT devices face is malware such as Trojans, viruses, and worms that can disable IoT systems. Each layer of IoT architecture has some security- and privacy-related issues, which we are required to be addressed in order to secure IoT applications. The potential capabilities of IoT can reduce a lot of time and expenditure of various organizations. These devices are excellent data collectors and sensors; therefore, they can help in efficient decision-making in a wide range of applications.