Ultra-Wideband (UWB) technology has gained significant traction in wireless positioning applications due to its high-precision ranging capabilities, robustness against multipath interference, and energy efficiency. Recent advancements have facilitated its integration into consumer electronics, particularly smartphones, enabling new positioning and tracking functionalities. This chapter provides a broad and detailed overview of the methodologies and technologies related to UWB positioning systems. The goal is to offer a comprehensive discussion of localization techniques, operational principles, and practical applications, covering both theoretical aspects and real-world implementations. A key contribution of this work is the in-depth technical description of Android Application Programming Interfaces (APIs) for UWB-based positioning with smartphones, providing valuable insights for developers and researchers interested in integrating this technology into their applications. Additionally, the chapter explores the standards and communication protocols that govern UWB technology, with a focus on the specifications adopted in various application scenarios, and the regulatory frameworks that are available today. By combining technical insights with a thorough analysis of existing methodologies, this chapter serves as a reference for understanding the potential of UWB technology and its impact across different domains, including indoor navigation, industrial automation, and smart devices.