The concept of an occludable anterior chamber angle describes eyes in which the peripheral iris is capable of obstructing aqueous humor access to the trabecular meshwork, either partially or completely. This chapter clarifies the distinctions between potentially occludable, partially occluded, and fully occluded angles, emphasizing the limitations and clinical relevance of these terms. Through meticulous gonioscopy, clinicians can identify subtle anatomic configurations, mechanisms of angle closure, and associated pathological findings critical for glaucoma diagnosis and management. The authors highlight that inadequate gonioscopic training leads to missed diagnoses and preventable vision loss, underscoring the essential role of expert angle evaluation in glaucoma care.