More than 1,000 international students at 128 colleges and universities have had their visas revoked or their legal status terminated since mid-March.

Students could bypass the United States for friendlier countries as the Trump administration attacks universities and revokes visas. Their loss could hurt schools and the economy.

How do student visas work? Coming to the United States for anything but tourism usually means wading through an alphabet soup of visa types – more than two dozen for people who do not intend to become permanent residents of the US.