mytrip sends a reminder that starting today, visitors to the US from 35 visa-waiver countries will be required to register online with the Department of Homeland Security in advance. The DHS is asking people to go online for the ESTA program 72 hours before traveling, but they can register any amount of time ahead. Approval, once granted, is good for 2 years. DHS says that most applications are approved in 4 seconds. If an application is rejected, the traveler will have to go to a US embassy and get a visa. CNet reports that information from applications will be retained for 12 years, and eventually up to 75 years.