At the moment, there is a new way to travel to the United State, which is a program called as the Visa Waiver Program or VWP made by the government. However, unfortunately, not everyone can travel to the State through this way. You will be able to use this new way only if you are a resident of the Visa Waiver Program who has an electronic passport and travel for a business purpose or temporary visit for less than 90 days, and complements all program requirements and has authorization obtained through the Electronic System For Travel Authorization which is abbreviated as ESTA.
You have to be a part of the citizens of the country that has become a member of the Visa Waiver Program to be able to use this system. Permanent residents of a country included as a member of The Visa Waiver Program is not qualified for the Visa Waiver Program unless they are also citizens of one of the other Visa Waiver countries.
That is the reason why there will be some of the visitors that may not be eligible to enter the US without a visa with VWP that can be obtained with an approved ESTA or Electronic System For Travel Authorization. This includes those who have been detained, also if the detention does not end up being a criminal charge, those with criminal records even if there are exceptions, amnesties or other deductions, serious communication deficiency diseases, those who have been refused to get the permit to enter the United State, or have been deported from the country, or have previously lived beyond the stay in the waiver visa program. The particular visitor, then, has to apply for a visa. If they try to travel without a visa, they may be denied to enter the United States.