The importance of each person's healthcare should be viewed as fundamental in the modern world due to the rise in various health issues. A decrease in the proportion of doctors is caused by an increase in the number of cases. The diagnosis is consequently delayed, or some patients are overlooked. As a result, people become more reliant on doctors for checkups. In order to retain each patient's digital identification, in light of all these worries, health and medical care systems have begun to connect and interact with the internet of things (IoT). Many health disorders in the healthcare system go undiagnosed resulting from a shortage of doctors and other medical experts, as well as a lack of access to healthcare services. These IoT-based healthcare options, on the other hand, have made it possible for patients and medical professionals to continuously track and analyze patient data. In this study, IoT for healthcare systems is discussed. These included applications, structures, and potential design snags and issues. It has been demonstrated that these systems could be very beneficial to people, especially during the (Covid-19) pandemic's global isolation and the growing challenges in treating patients intelligently. This paper also presents a survey study on the use of IoT in smart healthcare, its applicability, the future directions for its development, and a review of past researchers' applications.