When must I obtain a visa to travel to the US?

When must I obtain a visa to travel to the United States?

If you intend to arrive in the United States aboard a non-signatory air carrier.
If you intend to visit the United States for more than 90 days.
If you believe any grounds of inadmissibility of the Immigration and Nationality Act § 212(a) apply to you, you should apply for a nonimmigrant visa before traveling to the United States.
If you are traveling to the United States for a purpose other than short-term tourism or business.

Before applying, remember to have a photo of your passport, a credit/debit card or your Paypal account available.

If you have already submitted an application for one or more individuals, you can Check your ESTA Status.