What is Obamacare and why does Donald Trump want to repeal the Affordable Care Act?

What is Obamacare? Officially known as the Affordable Care Act, Obamacare was the flagship piece of legislation passed by the Obama administration in March 2010 and is regarded as his greatest domestic achievement.  It extended health insurance to millions of Americans who up until then had been uncovered. According to one estimate, as many as 50 million people gained cover. They were mainly people who were not poor enough to get subsidised insurance offered to the elderly and tho