Trataka is a yogic practice of steady, unblinking gazing at a single point or object, used to develop concentration, still the restless mind, and, in the traditional accounts, to awaken inner vision. The practitioner fixes the eyes on a chosen object, most commonly the small steady flame of a lamp or candle, but also a dot, a symbol, an image of a deity, or the rising sun or moon, and holds the gaze without blinking for as long as is comfortable, until the eyes water, then closes them and holds the after-image of the object in the mind's eye. The outward gazing trains the eyes and gathers the attention onto one point; the inward visualisation that follows carries that gathered attention into the mind, and the two together are said to build a powerful one-pointedness of concentration.
The practice is classified in the hatha yoga tradition among the shatkarmas, the six purificatory actions, where it is credited with cleansing and strengthening the eyes; but its deeper purpose is meditative. By giving the notoriously restless mind a single fixed object, trataka is used as a preparation for meditation proper and as a technique for developing focus, and the traditional texts associate its sustained practice with the steadying of the mind, the awakening of concentration, and the arising of inner light and, in some accounts, of subtle perception. It has been widely taken up in modern yoga and meditation instruction as an accessible concentration exercise, generally taught with the caution that the gazing should not strain the eyes and should be built up gradually.