On arrival in the USA, a person must show a valid national passport or other document satisfactorily establishing his/her identity and nationality. The passport must be valid for longer than the intended period of stay.
In general the following citizens do not need a visa to enter the USA as a tourist for 90 days or less.
Several European countries including the UK, Austria, Belgium, Denmark, Finland, France, Ireland, Italy, Spain, Switzerland and more..
NOTE: Currently, all visitors, except Canadians and certain Mexicans may have their finger prints taken, photo taken and eye scans.
All visitors, who do not need a visa, except Canadians and certain Mexicans, also need to fill out a Electronic System for Travel Authorization (ESTA) before travelling to the USA, either online or with your travel agent:
NOTE: These regulations are on going and changing all the time so please check the following official web site.