Why did the federal government shut down? Congress must pass a spending bill each year; if not, nonessential government services shut down.
Why now? The federal fiscal year ends on Sept. 30.
What’s behind this? Some Republicans in the U.S. House of Representatives want to stall or change implementation of the Affordable Care Act.
CNN expands on these and 17 other questions that get us up to speed on exactly what’s going on.