US has reciprocity with many nations, (Like Europe, Japan and Singapore), whose citizens can travel to the US without a visa. These people visit the US under the Visa Waiver Program. United States Citizens also can travel to these countries without a visa. The idea is that citizens of these countries will not remain illegally in the US, and it will facilitate travel, especially business travel.
From August 8, due to security reasons, US will be requiring all travelers under VWP to register online before leaving for the US. Once anyone registers and gets a travel authorization, it will be valid for 2 years. The questions will be the same required for an I-94 in the plane.
Europe is already contemplating similar actions for US travelers.
Hopefully this program will work and not result in fewer business and pleasure travelers to the US, resulting in fewer amount of money generated in the US.