The Internet of Things (IoT) vision enables multiple of resource-constrained embedded devices, objects, and humans to connect together through the Internet protocol for a ubiquitous data exchange. Logistics is considered to be a key player poised from this vision to achieve the full visibility and transparency through leveraging the pervasive interconnectivity to collect reliable and safe real-time data. In addition, the valuable information extracted and transformed from the IoT data can be exploited to create intelligent services and applications to improve the logistics activities as well as the overall performance of logistics operations. This paper aims at reviewing the state-of-the-art applications of IoT in the logistics sector. Although the adoption of IoT potentially gains huge benefits, there still exist barriers preventing the full adoption of IoT in the logistics. This paper also discusses such challenges that promise to expose a wide range of open research regarding the integration of IoT in the logistics domain.