The wave of popular uprisings that swept the Arab world were as unexpected as they were cataclysmic.  Long-reigning rulers fell, others teeter on the brink, and the region is forever changed.

The Arab Spring started with a death: in early January, protesters took to the streets of Tunisia in solidarity with a young fruit vendor who, despairing of the brutal system under which he lived, set himself on fire.

It was a death that gave life to a movement that was to alter the course of the Middle East and North Africa.

For decades, political life in the region was stagnant.  Nominal republics were the realm of a wealthy few, with kingly aspirations to see their sons carry on the business of state.  It seemed nothing would change, but then it all did all at once.

The revolt against tyranny, simmering for years, reached a breaking point.  For many, there was no turning back.

"One of the scenes that we've seen in many of the Arab Spring countries, first in Tunisia, then in Egypt, then in Libya and Syria are these images, usually of young men, who are willing to die for ideals of freedom, for notions of rights in front of security officials with guns in city after city and this new courage to stand up to abuse we have seen, really is what has fueled the Arab Spring," noted Heba Morayef of Human Rights Watch.

The protesters learned from each other, for to a large extent, they were fighting the same thing.  The very nature of leaderships that were so repressive proved to be their mutual undoing.

"They all had the same system - a military, intelligence, police state - like in Tunisia, like in Egypt, like in Yemen, like in Syria, like in Libya, the same system, so it is catching," noted Said Sadek of American University in Cairo.  "Once you have something affecting the domino, the whole dominoes is affected."

The uprisings changed not only the rulers of these states, but unsettled long-standing alliances.

"It's brought in this sort of sense of unpredictability about the Middle East which seemed to be such a stable region: authoritarian rulers would hand on power to their children in many cases and where the international community could rely upon having certain friends in the region who would guarantee stability.  I think those understandings of the Middle East have been broken," Morayef explained.

The jury is still out on whether the protests will bring the hoped for transition to representative governments.  Some see the rise of Islamist parties in Tunisia and Egypt as a threat to a democratic transition.

And for others in the region, the struggle continues.

But one thing is certain, these fearless young people have become a constituency, one every new Arab leader from now on must deal with.