The new presidential proclamation bans travel to the USA by most citizens of Chad, Iran, Libya, North Korea, Somalia, Syria and Yemen. Citizens of Iraq and some groups of people in Venezuela will face new restrictions or higher scrutiny.
Unlike the previous ban, this one is for an indefinite period of time.
The new ban isn't intended to affect legal permanent US residents, people currently holding valid visas, or people seeking refugee status.
New rules for refugees will be announced shortly.