The experience typically occurs after sustained practice and intense concentration, often triggered by some minor event or sound. The practitioner suddenly sees through the illusion of separate selfhood, recognizing the true nature of reality beyond conceptual thinking.
Satori differs from final enlightenment (bodhi). It represents an opening, a glimpse of awakened consciousness, rather than complete and permanent realization. Zen masters compare it to a first sip of water when dying of thirst—life-changing but not the end of practice.
Famous satori accounts include monks hearing a pebble strike bamboo or seeing a peach blossom, moments when the boundary between subject and object dissolves and one experiences reality directly. The ordinariness of triggers points to the accessibility of awakening in any moment.
D.T. Suzuki introduced satori to Western audiences, though some scholars debate whether his presentation romanticized or distorted traditional Zen understanding. Nonetheless, satori represents an important aspect of Zen's emphasis on direct realization beyond intellectual understanding.
Source
Zen Buddhism