Interrogation refers to the process of extracting information from a captive. Police often interrogate criminals, and in wartime, opposing sides may interrogate prisoners of war. Interrogation is often part of torture, and an interrogation chair is an aid to interrogation. Truth serums are sometimes administered during interrogations.
In 2371, Enabran Tain asked Elim Garak to interrogate Odo for information regarding the Founders. He used a device which emitted a quantum stasis field to inhibit Odo's ability to change shape. Although Garak was certain that everything Odo knew about the Founders had already been divulged, he nonetheless carried out the interrogation hoping to gain Tain's trust. Unable to change back into his liquid state, Odo began to degenerate until he finally divulged one secret to Garak that he had not revealed to anyone else: he wished to return to his people, the Founders. Ashamed of what he had been doing, Garak deactivated the stasis field, allowing Odo to regenerate and ending the interrogation. (DS9: "The Die is Cast")