After all this buildup, the defense in the states is rather anti-climatic. The student gives an extended talk on his thesis research, the thesis committee peppers the student with questions, then the committee deliberates and decides whether to pass the student.
The defense is mostly for show, the student almost always passes. If the student didn't deserve to pass the fault lies not with the student but with the advisor for letting the process get this far. A dirty little secret: We often make the deliberation longer than needed just to add a little drama.
I have served on defense committees in Denmark and Portugal that follow this same basic plan. But not all countries do the same.
I remember visiting the University of Karlsruhe (Germany) when a parade broke out. I asked about the parade and my host said someone just got their Ph.D. I have also heard of some countries where the advisor has to defend the thesis. Glad I don't teach there.
I bring this up because next week I sit on my third committee at the University of Amsterdam. The Dutch do their Ph.D. defenses the way the way a defense ought to be done. What happens at the Dutch defense? I'll let you know next week.