The Arab Spring began in Tunisia, with the self-immolation of a vegetable seller named Mohammed Bouazizi. This kicked off a wave of protests that ended with the ouster of Tunisian president Zine el Abidine Ben Ali. Similar protests (and self-immolations) soon followed around the Middle East/North Africa region. More information can be found in pretty much any newspaper and/or Wikipedia.
'Arab Summer' isn't defined...yet.--Urban Dictionary