What is the US debt ceiling and what will happen if it is not raised?

The White House and Republicans in Congress are currently in a standoff over how much the government can borrow

The US faces an unprecedented economic and financial storm", the treasury secretary, Janet Yellen, warned on Tuesday as Joe Biden met with his Republican counterparts for the latest in a series of tense talks over the US debt ceiling.

Time is quickly running out to find a solution, said Yellen. Without raising the debt limit, the US government will default on its bills, a historic first, with likely catastrophic consequences. Federal workers would be furloughed, global stock markets would crash and the US economy would probably drop into a recession.