What is a recession, and is the U.S. economy heading for one? Here's what economists say.

President Trump sparked concerns this week when he declined to rule out the possibility of a U.S. recession this year. Asked on Fox news if he expects such a slump, Mr. Trump said, "I hate to predict things like that. There is a period of transition because what we're doing is very big."

U.S. Commerce Secretary Howard Lutnick also seemed to leave open the possibility of a downturn, telling CBS News in an interview on Tuesday that Mr. Trump's economic policies are "worth it" even if they lead to a recession. 

While it is notoriously hard to predict a recession, there are definitive criteria that must be met in order for a business cycle to be considered recessionary. Here's what to know.