The world economic crisis - a Simpleton explanation
In order to pay for things like welfare services and their military, governments must tax people to pay for it. Like you do for your family at Christmas, so governments borrow money to pay for extra goodies. In order to pay their debts, so they need increased revenues from tax – and rely on people like you and me to earn more, and thus pay more tax. When the economy goes tits up, so some countries struggle to pay their debts.