In the relentless pursuit of extending our sensory reach beyond classical limitations, quantum sensors strive to redefine boundaries of detection and measurement. The Rydberg atom stands as a leading physical platform for quantum sensing of electromagnetic fields, featuring access to an ultrawide spectrum from essentially static fields to the optical region with exquisite sensitivity, particularly at radio frequencies. Rydberg quantum sensors employ atomic vapors and laser fields to exploit highly excited Rydberg states of atoms with exaggerated properties and tunable interactions with radio frequency (RF) fields from DC to THz, enabling pathways to new RF capabilities and quantum technologies for electric field sensing, precision measurement, and imaging. I will present an overview of Rydberg quantum sensing, including atomic physics and quantum-optics methods and techniques underlying their operation and summarize the state of the art in sensors for real-world applications, from antenna measurement probes to the recent demonstration of the first long-range signal reception and communication with a suit-case-sized Rydberg atomic receiver.