During recent years, one of the most familiar names scaling new heights and creating a benchmark in the world is the Internet of Things (IoT). It is indeed the future of communication that has transformed things (objects) of the real-world into smart objects. The functional aspect of IoT is to unite every object of the world under one common infrastructure; in such a manner that humans not only have the ability to control those objects; but to provide regular and timely updates on the current status. IoT concepts were proposed a couple of years ago and it may not be incorrect to quote that this term has become a benchmark for establishing communication among objects. In context to the present standings of IoT, a comprehensive review of literature has been undertaken on various aspects of IoT, i.e., technologies, applications, challenges, etc. This paper evaluates various contributions of researchers in different areas of applications. These papers were investigated on various parameters identified in each application domain. Furthermore, existing challenges in these areas are highlighted. Future research directions in the field of IoT have also been highlighted in the study to equip novel researchers in this area to assess the current standings of IoT and to improve upon them with innovative ideas.