For the first time, fighters from all the big Kurdish factions in the Middle East, the whole alphabet soup of KDP, PUK, PKK and YPG, will be fighting alongside each other in the same battle – the defence of Kobane from Isil in Syria. For the Kurds – who aspire to statehood, it's a hugely powerful moment. But just who are all these factions, and why do they matter?: