The Internet of Things (IoT) is revolutionizing the manner in which devices interact, enabling smart environments in sectors such as healthcare, transportation, and power grids. However, this growing interconnectivity comes with serious cybersecurity challenges with the vast number of interconnected devices, limited computing resources, and lack of standardized security practices. This review addresses the most significant cybersecurity threats in IoT environments, particularly in critical infrastructures such as the smart grid, where device compromise can have catastrophic consequences. The article covers threats such as weak authentication, insecure communication, lack of encryption, and limited device security. It also covers secured device manufacturing practices, hardware protection, and networklevel controls. The article also includes a case study of web interface attacks to illustrate realworld threats. Since traditional security controls will be inadequate, the article emphasizes the importance of the use of newer methods such as machine learning and postquantum cryptography to predict, detect, and counter threats. In the future, the research urges developers, manufacturers, and researchers to collectively act with urgency to build scalable, secure IoT systems. With more widespread use of IoT, these cybersecurity issues need to be addressed in order to preserve the trust, reliability, and resilience of connected devices and critical services they deliver. Keywords: Internet of