Currently, citizens from 38 countries the U.S. deems low-risk can travel in the States up to 90 days without a visa after they're screened by Homeland Security and Customs.

Now citizens of those countries who "have traveled to or been present in Iran, Iraq, Sudan, or Syria on or after March 1, 2011" or are also nationals of Iran, Iraq, Sudan or Syria can no longer travel or be admitted to the U.S. under the Visa Waiver Program.

Travelers who went to those countries as journalists or for aid work or business can apply for a waiver.

To come to the U.S., these travelers will have to apply for visas at U.S. embassies or consulates, just like those who aren't part of the Visa Waiver Program.

This video includes images from Getty Images.