The Supreme Court won't revisit President Trump's temporary travel ban until October, but a lot will happen before then that could affect the travel of millions of people around the world.

A scaled-down version of the travel ban that was approved by the court and goes into effect Thursday bars U.S. entry for citizens of Iran, Libya, Somalia, Sudan, Syria and Yemen without prior ties to the United States.

The administration also has started a review of anti-terrorism vetting procedures used to screen travelers from all countries, and that could prompt more travel restrictions against a greater number of countries.

Immigration advocates are preparing lawsuits in case they believe the government exceeds legal limits in the actions it takes.

Here's what you need to know about the next steps for Trump's travel ban: