Tehran on Saturday blasted U.S. President Donald Trump's travel ban on countries including Iran, saying it showed "deep hostility" toward Iranians and Muslims. "The decision to ban the entry of Iranian nationals - merely due to their religion and nationality - not only indicates the deep hostility of American decision-makers towards the Iranian people and Muslims but also

The ban, which revives a controversial measure from Trump's first term, took effect Monday morning. Here's what to know about who's affected, who's exempt and how foreign leaders are responding.