Diagnostic imaging provides the visual language clinicians use to see internal structures and disease processes noninvasively. This text reviews modalities — X-ray, CT, MRI, ultrasound, nuclear medicine, and interventional imaging — explaining physics, protocols, and interpretation basics. Case examples demonstrate how imaging findings map to anatomy and pathology, with guidance on common artifacts and pitfalls. Sections on radiation safety, contrast media, and imaging workflow make it practical for clinical use. Designed for students and early-career clinicians, it balances technical foundations with everyday diagnostic decision points.