In most defenses you first summarize your research and findings in a brief talk, then answer questions from the committee and from the general audience. You and the audience are then asked to leave the room while the committee members discuss the defense. The committee will then ask the student to return to hear the result.
Since thesis/dissertation defenses are open to the public, you may want to attend a defense or two to see the format and process and learn what to expect. You can find a listing of defenses on the University Events Calendar or on the Graduate School website.
Committee members commonly ask for revisions based on points that come up at the defense. Keep careful notes so that you are clear on which revisions are required by your committee. You must complete all required changes and have them approved by your committee chair before you can deposit your thesis/dissertation.
Once you have made all changes required by your committee and your thesis/dissertation has been approved by your committee, the members will sign the Outcome of Defense form. This certifies to the Graduate School that you have satisfactorily completed the requirements of the department for the thesis/dissertation.