Glenoid bone loss significantly affects outcomes in shoulder instability surgery and arthroplasty. Recognizing and addressing glenoid bone loss is essential to reduce the risk of recurrent instability, implant failure and early revision. Advances in biomechanics, imaging, preoperative planning and surgical techniques have changed management strategies over the past two decades. Clinical decisions remain challenging, and must be patient-specific. This review provides an evidence-based overview of glenoid bone loss assessment and management. It focuses on two main areas: recurrent shoulder instability and primary and revision shoulder arthroplasty. For instability, the pathoanatomy of glenoid and bipolar bone loss is discussed alongside clinical assessment, imaging strategies and thresholds for critical and subcritical defects. The role of the glenoid track concept in refining risk stratification and guiding surgical decision-making is examined, with emphasis on selecting between soft-tissue stabilization, remplissage and bony augmentation procedures. In arthroplasty, patterns of glenoid bone loss, classification systems and advances in three-dimensional imaging and preoperative planning are reviewed. Contemporary management options for both anatomic and reverse shoulder arthroplasty are explored, including bone grafting, augmented components and custom solutions. Accurate assessment and patient-specific strategies are central to the successful management of glenoid bone loss.