In this talk on Hypersensitivity Pneumonitis (HP) by Dr. Jonathan Chung, several key points are discussed. The focus is on the recently published multisociety multidisciplinary guidelines for the diagnosis of HP, including an emphasis on imaging, particularly high-resolution CT scans, as crucial in the early stages of diagnosing HP. The talk advocates for a shift in categorizing HP based on morphology (fibrotic vs. non-fibrotic) rather than temporality. The three-density pattern is introduced as a replacement for the head-cheese sign, being highly suggestive of HP, especially in fibrotic cases. The presentation stresses the importance of recognizing typical patterns in both fibrotic and non-fibrotic HP cases and familiarity with the current guidelines for a comprehensive understanding of their diagnostic approach.