This chapter briefly introduces the principles of ultra-wideband (UWB)-based positioning, including four UWB positioning modes and their working mechanisms: time of arrival (TOA), time difference of arrival (TDOA), received signal strength (RSS), and angle of arrival (AOA). It then focuses on integrated positioning methods combining inertial measurement unit (IMU) and UWB, covering techniques such as Kalman filter (KF), extended Kalman filter (EKF), federated Kalman filter (FKF), and factor graph optimization. Furthermore, it presents multisource fusion positioning methods by integrating UWB, IMU, and global navigation satellite system (GNSS) to achieve continuous localization in both indoor and outdoor environments. The integration of UWB with GNSS and INS enables resilient, high-precision, and continuous localization capabilities in both indoor and outdoor settings. These methods lay the foundation for reliable positioning solutions in fields such as robotics, autonomous navigation, and logistics tracking.