Extending the current Internet and providing connection, communication, and internetworking between devices and physical objects, or "things," is a growing trend that's often referred to as the Internet of Things (IoT). Integrating real-world data into the Web, with its large repositories of data, and providing Web-based interactions between humans and IoT resources is what the Web of Things (WoT) stands for. Here, the guest editors describe the Big Data issues in the WoT, discuss the challenges of extracting actionable knowledge and insights from raw sensor data, and introduce the theme articles in this special issue.