"Kettling"

I posted something earlier about the austerity protests in Britain and France.  As this article shows, my and others' sense that the British would simply accept social welfare cuts with a "stiff upper lip" failed to consider the student population.  British students have indeed taken to the streets in considerable numbers to protest rising tuition and education cuts.  Police officers have been playing a cat-and-mouse game with the protesters.  In some cases, they have herded the students into pens.  This strategy of containment has been referred to as "kettling," a term I had not heard before.  Students have responded to kettling by engaging in less centralized assemblies, and by using social networks to evade police spatial tactics.