An orb experience refers to visions received when a person encounters a Tear of the Prophets. Experiences varied in intensity and duration.
Orb experiences are also possible when viewing the Orbs of the Pah-Wraiths. Cardassian resistance fighter Skrain Dukat was forced to look into a Pah-Wraith Orb during his captivity on Bajor, and was shown visions of alternate selves that succumbed to the will of the Pah-Wraiths. Prayer to Oralius disrupted the Orb mid-vision. (Sigils and Unions: Catacombs of Oralius--"Exits in the Haze")